No, the style is unnecessary, it's fine to have a round yellow one and then have a small realistic human head wearing a party hat. It's a forum, not the front page.
I just suggest we try to use unique emoticons, none of that stock crap people use regularly, it's not difficult to make these suckers and having unique emoticons is better than just a bunch of random ones from various sources.
Also it brings up the prospect that if something stupid happens here we can create an emoticon to remember it by.
EDIT: It's not too hard to tidy something like this up :
And turn it into an emoticon.
EDIT 2: Holy butt, well there you go, easy as pie.
Now if you're pissed you can have Doom Guy express it for you.