Cold Calling on the Button

[Kyle]

I breifly watched last night's 2+2 game and I noticed Bicyclekick doing something that I almost never do. He was cold calling raises on the button with hands like QJo and A9o. Usually if I am in a sitituation like that it is three bet or fold preflop. What is the merit to cold calling instead of three betting? And also what kind of sitituation do I need to look for to make this play profitable?