To have sex with a friend or acquaintance's mother; Usually as part of a single, ill-advised, drunken episode. Sometimes resulting in unplanned pregnancy.
Origin: rumors that James Doohan (actor of Star Trek fame) commonly had sexual intercourse with the mothers of his Star Trek castmates (crew). He was known to do this while spouting double entendre involving warp nacelles, phasers, or tractor beams.
Sorry, man. Your mom looked so good last night, I beamed myself over her house and 'pulled a Doohan'!