One of many euphemisms for "masturbation" (e.g. slappin' the salami, jack off, beat off, buffing the bishop, glean the obscene bean, choking the chicken, spanking the monkey, waxing the wonker, greasing the guppy, shooting putty at the moon, and Rosie Palmer and her Five Sisters doing the Four Knuckle Shuffle.
Frank will be a little bit late. He's still back at his house jackin' the beanstalk.
When one inserts both testicles into a woman's vagina whilst vigorously jackin' off on her abdomen, hence the name.
Just like Jack and HIS beanstalk, last night I carefully planted my two seeds and was Jackin' the beanstalk all over Mary.
pretty self explanatory. An act of jerkin it, or tuggin the bugger. Otherwise known as masturbation
Jon: "Yo, did you do your english assignment last night?"
Me: Nah man, I was preocupied jackin the beanstalk.
Jon: You been jackin the beanstalk AGAIN?!
Me: 3 times a day bro.