usually said when you are excited.

The following is as it relates to a video game, playable for Xbox and PC. "Woot Woot Woot" is the sound that the covenant elites make as they charge you in Halo CE. (combat evolved) Some people think that all of the aliens in the game speak backwards. That would make them say a version of GO GO GO.
Could be related to wOOt. From D&D meaning Great,(wow) Loot!

this phrase can be used anytime while excited or specifically happy.

can be used to describe having a party, or literally "party time"

Stands for: Waste Of Our Time.

Often used before work meetings to feign excitement for a really boring meeting.

1. excitement 2. reaction 3. totally awesome expression

An informal phrase used to imply satisfaction, agreement or happiness when used as a standalone sentence fragment.

Has increased in popularity over the past few years because of its various sexual connotations.

Geek speak that is used when said user is happy.