1) to steal something that you originally gave up from the person to which you gave it, usually in a clandestine and unjust manner (refers to the 2010 "Tonight Show" controversy).
2) to come out of retirement when in reality, no one wants you back See also: "to pull a Brett Farve"
Joey quit the baseball team and was replaced by Brandon. However, Joey snuck drugs into Brandon's locker, got Brandon kicked off, and regained his spot on the team. Joey just had to pull a Jay Leno on us.
"Definition 2" Example:
Our bitch of a computer keyboarding teacher had to pull a Jay Leno when she retired in 2009 and came back in 2010 when she realized that she had nothing better to do in life.