Incorrect on "jerk".. It isn't a reference to self-pleasuring, it's descended from "Soda Jerk". When carbonated drinks first came along, they didn't have bottles or cans, they had "Soda/Malt Shops" where the drinks were mixed in front of you with your choice of ingredients. The people who fixed the drinks and "jerked" the taps to carbonate them were called "Soda Jerks". They were typically teenage men, and the name ended up abbreviated when calling them from across the bar, "Hey Jerk!".