used for texting/online chat "er" is an abbreviation for "eyeroll"; when someone does or says something that makes you roll your eyes you "er" at them; it can also be used in place of the term "oh, whatever"
er is a word used by jocks in Dublin to basicly piss off somybody they dont like or to burn them.also the term er mates is used to say, "you have no friends"
loser:"hey i just got a new calculator"
jocks:"er!!!"