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.
Eric - Yo bro, I'm so stoned.
Dave - Same dude. Wanna do Kush ups?
Eric - Yea bro. Let's do it.