jackin' the beanstalk
When you're too lazy to use your hands and just use your imagination to pretend you're Jack from the beanstalk story, but you're really just jerkin' it.
At school, I was jackin' the beanstalk under my desk during math.
My brother was jackin' the beanstalk while pretending to read a book.
I was jackin' the beanstalk in the car, and my dad was so mad.