:) - a smiley face emoticon, displayed randomly.
0 - a large number zero originally giving Zer0 his nickname. It is displayed after an enemy is killed with a melee attack.
:D - a smiley face emoticon, displayed when constructing and/or entering a vehicle at the Catch-A-Ride station.
WTF BRO - an acronym for "What The ♥♥♥♥♥, Bro," displayed after crashing a vehicle into something.
<3 - a heart emoticon, displayed while reviving a friendly player.
FML - an acronym for "For My Loss" or "♥♥♥♥♥ My Life," displayed after being crippled.
? - a question mark, displayed when pending actions (such as switching seats with a player in a vehicle) or when viewing the map.
! - an exclamation mark, displayed when seeing a downed friendly player.
$ - a dollar sign, displayed when completing a mission.
&& - twin ampersands, displayed when inspecting items in the menu.
勝 - a kanji character meaning "victory", displayed when receiving items by either picking them up or via trading.
... - an ellipsis, displayed when either inspecting menu items, after killing an enemy, or while reloading a weapon.
:l - a straight face emoticon, displayed when standing idle.
ZZZ - three Zs, a common emote for "sleeping," displayed when standing idle.
:( - a sad face emoticon, displayed when standing idle.
B0R3D - the word "BORED" written in leet speak, displayed when standing idle.
嘆く - a kanji character meaning "sigh," displayed when standing idle.
OWND - an abbreviation for "owned," displayed after killing an enemy with a critical hit.
止 - a kanji character meaning "stop" displayed when trying to fast-travel while a co-op partner has a menu open.


00110000 - the binary ASCII code (48) for the digit 0.
:(_8(1) - an emoticon looking like Homer Simpson from the TV-show The Simpsons.
>_< - a frustrated person emoticon.
:-P - a person sticking their tongue out as an emoticon.
:-D - another smiley face emoticon.
>:-] - an evil face emoticon.
[O][O] - two wide eyes as an emoticon.
[.][.] - a female breasts emoticon.
^5 - an emoticon symbolizing a "high five."
D13 - the word "DIE" written in leet speak.
K1LL - the word "KILL" written in leet speak.
1337 - the word "LEET" written in leet speak, which can also mean "ELITE."
PA1N -the word "PAIN" written in leet speak.
W34K - the word "WEAK" written in leet speak.
3MTA3 - the words "EAT ME" written backward and in leet speak, which was a saying made famous by Beastie Boys, a hip-hop band.
4SS4SS1N - the word "ASSASSIN" written in leet speak.
<-SHOOT - an arrow and the word "SHOOT," telling one where to shoot.
WTF - an acronym for "What The ♥♥♥♥♥."
OMG - an acronym for "Oh, My God."
LOL - an acronym for "Laugh Out Loud."
GTFO - an acronym for "Get The ♥♥♥♥♥ Out."
\M/ - The "sign of the horns."
\0/ - a person with their arms in the air as an emoticon.
!!! - three exclamation points.
42 - the "Answer to the Ultimate Question of Life, the Universe, and Everything."
666 - the "number of the Beast."
31415 - the first five numbers of Pi.
8675309 - a phone number, referencing the famous song "867-5309/Jenny", performed by artist Tommy Tutone.
8===D - the number 8, three equal signs and the letter D, a common text representation of male genitalia.