The act of doing push ups while smoking weed. To participate in Kush Ups, take a hit, and hold it in while doing push ups. You must hold it in until the next participant takes their hit. If you cannot hold it in, or if you cannot continue doing push ups, each participant gets the right to call you a bitch for the remainder of the night.

when you're hungover as shit after a spending a night drunk as a skunk

A Kush up is a very small hit of a joint. Experienced people in Kush ups can do multiple at a time. For instance 30 Kush ups = 30 continous small hits without blowing out the smoke, only at the end you are allowed to breathe again.

The act of performing a pushup while elevating oneself by exhaling kush.