Mainly the lag is the main reason online isn't as fun as it could be. Tea bagging is just a dick move. And fatalities are okay but if I'm playing someone in a string of matches and they just keep doing it. That's annoying because if your having good matches you wanna get right to it. And not wait for a fatality you've seen countless times. Besides that spammers are tolerable its kinda fun trying to find a way around it.
wat annoys me the most? this makes my blood boil:
have you ever fought someone and raped them, then they quit and start spamming in the lobby about how THEY BEAT YOU? and start saying you suck and ***** this, puss y that? God I HATE that sooo much. its soooo dumb and immature. I usually just reply by flippin out, then saying the bubble on the right doesn't lie about who won. IMDEADYES on psn does this on a daily basis