A classic ASCII art thought bubble as found in comics, also comes in shortened forms:

.o(thought)

oO(idea)
.O(eureka)
o(really?)
.(hmm)

… and can contain other ASCII art instead of text.

An emoticon used to represent an e30 BMW.

Burmese slang for genitalia.

emoticon: denotes the face of a happy little piggy

Out Of Stock. As in, a retailer is selling something and they ran out of it.

Out of Sync. Problem that used to plague Age of Mythology's online matchmaking service, ESO, until a patch fixed it. Any one player being "out of sync" would crash the game for all players involved. Only comes up now in rare instances.

it a emoticon for a nintendo controller. the left bracket is a side, the + is the d-pad, the two - - are the select and start keys, the two o o are the B and A buttons, and the end bracket is the other side of the controller.