The Three B's refer to the three things we all need in life. Just ridin the wave of life, and lettin the surf suck me off. I chew Nicorette Gumwhatever.
Another of the thousands of euphemisms that describe male masterbation. The term comes from the act of loading a catapult like medieval weapon called a trebuchet which used counterweights, and mechanical advantage to hurl things long distances.
Sally caught Dave loading the trebuchet to a Britney Spears music video and immediately dumped him.