A new brand of cough medicine similar to Robitussin DM that was placed into the market by American rapper Lil' Wayne, a.k.a. Weezy, hence the combination of Robitussin and Weezy (Wetussin). This OTC cough preparation can be purchased at any drug store by the handle and bears the image of Weezy holding a trident posing as Neptune, Greek god of the sea.
Fan: Yo Weezy, I tripped on that shit too and thought I was Neptune!!!!
Weezy: Hey, this guy recognized my lyrics, give him a free handle of Wetussin!!!!
A term first invented by Cher, then popularized by Youtube. Thanks to someone with no life, you can listen to wagon wheel watusi for 10 minutes. Thanks guys.