Ah, the TF2 soundfile, the gift that keeps on giving. Here's a remix of Heavy crooning "Babyman", a sendup of Lady Gaga's chart-topper "Pokerface", Warning, 30 seconds of this is enough to get both songs stuck in your head.
Credits also to Medic and Spy for some of the vocals. But Heavy makes it clear this is his song, not theirs.
Heavy Weapons Guy - Babyman (Pokerface) [YouTube, thanks Dylan M.]