Okay uh, so this is my problem.

I think I have an ego. I mean it's hard to explain (I'm a rhythm guitarist) but I keep, sort of, 'wanting more'. Like, I get a little bored easily if the song is repetitive and stuff (we do mostly covers).

Also another thing, the drummer and lead guitarist (there are five people in the band) likes to play songs by themselves, songs that none of the band knows and stuff, and they like popping last minute stuff in without any agreement and stuff (this is done usually over a message on a cell phone and sometimes the message doesn't get through). Soo sometimes, I really can't be bothered to give my 100% on those songs they randomly pick for us. Should I always give it my all at times like these? Because whenever this happens its like those guys really give a **** on playing songs they like as opposed to sort of a 'band agreement'.

Yeah is this really how an egotistical prick thinks? And if it is, wtf should I do to repress this assholeness from erupting through my head?

Oh and, I have to say, I DO still have fun in the band besides little trivialish stuff like this, 'cause we're all friends and used to go to the same school and we just mess around usually before and after practising and I really love those guys in a non-sexual way, so I really need to know if I'm turning into a prick.
Well, Spice it up then. If your bored, Head Bang. Also tell them to get their **** in order. They cant just pop **** on you at the last second. Granted you should still give it your all. But they cant hold you to it if you dont have it down completely.
I think it's completely fair for you to be kept in the loop as to what songs you'll be playing, and, for that matter, that you are part of the decision making process for which songs to play. Even though you "only" play rhythm guitar, if you guys are going to be a successful band, you need to communicate properly.

That said, you should be playing full intensity, unless you have a reason not to. Should you have a good reason, let the other guys know, for instance if you hurt your hand, your cat just died, or if the song is just plain boring. Rhythm guitar can get pretty stale on it's own, it wouldn't hurt for you to vary your parts slightly to keep the song varied, or even add some backing vocals here and there (you didn't specify whether you sang or not).
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I do sing backup sometimes. Though I don't really know if my vocals are all that good, I mean, I don't really wanna wreck a song if my singing is bad.

Plus I get kinda self-conscious when I sing.
its normal to get self conscious about everything when ur on stage

my singing really really sucks....so i do like a jimi hendrix kinda singing...where its really not singing

as for my guitar playing...sure im nervous if people like it or whatever...but if they dont then they just dont have good taste (from my point of view) and dont have the talent to do what i just did anyways

so dont worry about that

but let the band know you wanna be counted in and its a band! everyone has a key role and has say so

and for the rhythm if you can keep the beat and do it right you can add in little melodies to the chords or whatever
Just let them know that you want to have more of a say in the band in song selection, if they're your friends and are good bandmates they'll agree. If not, quit, you deserve an equal say, if you want try to get everything unanimous in the band before finalizing it.
It doesn't sound to me like you have an ego, it just sounds to me like you're aggrivated that other band members want to do their own things in the context of the band that you may not agree with, which is totally understandable. Make it a point to them that you don't really like what they are bringing to the table, and at the same time bring your own stuff to the table because if you don't have anything to uproot their crappy shit they won't really give a fuck.
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