Said by Patrick in the Spongebob episode "Hall monitor" Wee woo expresses great emotion, in Patrick's case it is fear. It is also the sound that police officers make when they do not have sirens. Or like Patrick are scared and say it to remind themselves that they are tough police officers :D

The word weewoo means a stupid or a dumb person.

Wee woo is the sound a siren makes. It is used in jest, to make fun of police cars, fire engines, ambulances, anything with a siren, really. Popularized by short films.

The sound that sirens make.

1. The emotion you feel when you are stuck in a awkward position and you have nothing else to do.
2. The sound you make when you know you are gonna get pwned.

An ambulance,
or an emergency.

wee woo is like greeting someone like hello