[censored] 2 late
ok uhm

brb = be right back
lol = laughing out loud
wb = welcome back
rdy = ready
lmao = laughing my [censored] off
rofl = rolling on the floor
col = crying out loud
ty = thank you
irl = in real life
asl = age, sex, location
ttyl = talk to ya later

and there are lots more ;p