here's some examples of telltale signs that your friend may be not of the homo sapiens species. and genus, to be pedantic:
1. sleeping more than 18 hours a day. this is ridiculous. i know some people are getting old (points away from myself). but 18 hours. really. it's like bejamin button took a crap in my breakfast and decided to infect me with whatever... thing... he has. and no, i don't know if it's transmissible in that way, get off my case. and while we're on that, that's another thing, i totally... zzz...
2. metabolic activity drops to -10 when it's cold. i used to love the cold. it sure as hell beats the tropical sun blasting uv death into your face every day of the year. but then, i had to go and study in the uk. and sweet frostbitten toes jesus does winter suck. i take back everything i have ever said to belittle the sun. everything. in fact, let me say it up straight, right now: mr. sun. i love you so much. even more than a mother loves her newly born child. even more than how fat kids love chocolate. even more than how there is love lost on fermina. seriously, never leave me again. ahem. and snow is the work of the devil. how ironic is that. fez will tell you more about this (i don't remember if i've got this episode right, and the internet is super slow here at my
... which has absolutely nothing to do with that metabolism thing i was talking about... but never mind this. you get my drift.
3. eating everything in sight. apparently, it goes both ways (that's what she said, oh!). some people eat loads when they're sick and some people eat nothing. so, we can't really say that someone might be an alien based on how much (s)he eats. however, what that person eats is a very telltale sign - just like a chameleon, these potential aliens will eat anything and everything. i kid you not. i mean, just the other day i ate 5 day old rice. 5. day. old. it tasted horrible, but at the time it didn't feel that way. then there's the attempt to eat oyster. now, don't get me wrong, a lot of people enjoy eating slimy, bacteria-and-virus-laden, toxic muscle of stomach agony. and that's fine with them. but for someone who has tried it and actively despises such vile and rancid things, even attempting to try it was... ugh.
4. the power of persuasion. come on. any good spy should be able to change your mind by some means or another. i'm talking jedi mind tricks. men who stare at goats. socratic logic. don corleone threats. whatever it takes. but, all these are human-based and are flawed. real aliens do it hypnotoad style. all bow to hypnotoad.
5. forgetting things. yea, i know it's pretty common for infections to effect your mind. especially with cases of upper respiratory tract infections, which go on to have meningitis effects. but the, you have that really awkward thing where you are in mid sentence and forget what you were... wait, what was i saying?
6. secretly going missing every few hours. for me, this was disappearing to the wc and flushing from my system the contents of lunch. breakfast and last night's dinner, too, sometimes. i'll spare you the details. but, in the case of alien chameleons (who obviously don't use the toilet, like humans do), they'll disappear all the time to an undisclosed and unknown location. which, i hypothesise, is to their secret beam-me-up-scotty devices to transmit useless information back to the mother-brain.
check if your best friend has one of these in the backyard.
7. blanking out every once in a while. i'm embarrassed to say this, but when i'm thoroughly sick, i can't control myself. kind of like barney in a bar with hot chicks. college-girl-five. but yeah, i'm not talking about libido (although, we could move on to this, next, if that's your kind of thing. and you're of the opposite gender). ahem. sometimes i'm just walking along and feel a mild attack of postural hypotension coming along (you can tell i spend most of my sick days in bed). then. boom. nothing but black. and i find myself on the floor wondering how i got there, with memories vaguely coming back, accompanied by the throbbing pain that radiates from the spot on my cranium where i hit the floor first. which sometimes happens to be on my forehead. great reflexes there, i know. and how this relates to alien chameleons. well, from watching the discovery channel, apparently, they fall off trees randomly sometimes. and i can only imagine them going through the same thing, except for them this isn't because of sickness, but is a normal happenstance.
8. inane infatuation with mundane things. wow. this pencil. it's amazing!
9. forgetting things. yea, i know it's pretty common for infections to effect your mind. especially with cases of upper respiratory tract infections, which go on to have meningitis effects. but the, you have that really awkward thing where you are in mid sentence and forget what you were... wait, what was i saying?
10. changing colours. you may wonder why i have left this 'til the last part. chameleons and changing colours. duh. but this would be wayyyyy too obvious a giveaway. come on, humans going purple, green, yellow, or any other colour of the rainbow. well, purple isn't a colour of the rainbow, i get it, calm the eff down. violet. there. here, have a picture of a rainbow lightning, just because it's awesome.
but yeah, i'm not talking about literal colours. more like mood, affect and all that psychological jazz. if you've seen a pms-ing chick, you know that moods can swing like a 40's jitterbug. and sick people have reason to do the same. well, really sick people.
now, alien chameleons were never brought up to deal with emotions like humans were. heck, even some humans weren't. but anyway, chameleons aren't on best terms with emotions. so if you see someone just randomly changing from emotional blue to emotional green to emotional red. something's probably up.
and that's it. god, that was long. i'm not an alien.