Never a hat-trick, but I've pulled many double-bumps over the years.

My favorite bump story similar to Live4Miles' mom: we were flying DEN-SFO in 2000 on an oversold A320. We were seated in bad coach seats in the back when they asked for volunteers. Since people were already seated, nobody moved, but we jumped up to take the $200 - just to get out of our awful seats. We walked off the jetbridge, the agent hurried us along with vouchers and boarding passes on a flight leaving 20 minutes after our scheduled one. We didn't pay much attention to the seat assignments until we walked onto the next flight: it was a 747 and we were upstairs in business class!