A person getting a BJ while jumping on a trampoline. The one giving the job gets his/her mouth full of saliva and penile fluids, and then drools it all over the male scrotum. When finished the flailing scrotum will resemble a rabid jellyfish.
Boy: Wow, grandma, that was a mean rabid jellyfish you gave me last night. It gave me so much duck butter it was hard to sleep.
Grandma: Just giving you a little taste of the 20s boy.