Full List of Internet Abbreviations*
*= not complete, will it ever be?

u/j00- you
r- are
ur- your/you're
itz- its/it's
l8r/l8ter/l8rz- later
2- too/two/to
4- for/four
gr8- great
8- ate/eight
1- one/won
w8- wait
no- know
thanx/thx- thanks or thank you
nd/n- and (there are two uses of "n")
cuz- 'cause or because, occasionally: cousin
bcuz- because
dum- dumb
ges/gess- guess
wat/wut- what
wit or w/- with
jus- just
4got- forgot
cya- see you
sum- some
sumthin- something
yea/yeh- yeah
ryt/rite- right/write
sk8- skate
sk8r- skater
gr8d- grade
tink- think
dem- them
ova- over
n/en- in
cum- come
mi- my
ne/NE- any
ne1/NE1- anyone
NEmore/NEmor/nemor/nemore- anymore
NEtime/netime- anytime
NEwayz/neway/newayz/NEway- anyways or anyway
sum1- someone
b4- before
kewl/kool- cool
tyme- time
eva- ever
4eva/4ever- forever
hoo- who
ov/uv- of
den- then
bak- back
her/heer/hea- here/hear
ben- been
were- where
wer/wur- were
holla- holler
thru- through
crzy/czy- crazy
sux- sucks
sry/srry- sorry
iz- is
lo- low
hi- high or just regular hi
hav- have
wel- well
rok- rock
rox- rocks
plz/pls/pleeze/plez- please
ppl- people
tho- though
grl/grrl/gurl- girl
neet- neat
ive- I've
dood- dude
peep- friend/person
dat- that
yr- year
luv/lov/lv- love
lik/liek- like
da/teh- the
wuz/waz- was
m- am
@- at
sox- socks
skool/skul- school
1337- literally, leet, short for ELITE
pwned- technically a typo of "owned"... You say it when you prove someone wrong or make a good point to another person
wutev/wutever/watever/watev- whatever
boi- boy
dis- this
k- okay
o- oh
c- see/sea
y- why
b- be/bee
lol- laugh out loud
holla ba(c)k- please reply or just 'reply'
contractions- they can be different besides this, but they don't have apostrophes in them
wu/wuz^/wazzup/wuzzup/whats^/waz^- what's up
something-Z- this one means a Z on the end of a word that normally ends in S
asap- as soon as possible
pdq- pretty darn quick
pp/ppt- please post (this) (message boards)
nmh/n2mh- not much here/not too much here
jk or j/k- just kidding
imo- in my opinion
omg- oh my gosh
bbl- be back later
idk- I don't know
fsr- for some reason
lylas- love you like a sister
brb- be right back
ttyl- talk to you later
ttys- talk to you soon
ttfn- ta-ta for now
g2g/gtg- got to go
wth- what the heck
rofl/rotfl- rolling on the floor laughing
lmbo/- laughing my butt off
roflmbo/rotflmbo- rolling on the floor laughing my butt off
fyi- for your information
btw- by the way