The ones I regularly go for
- Sober - Nanowar of Steel
- Murmaider - Deathklok
- We Got The Moves - Electric Callboy
These songs help the digestion by non-metalheads by being very funny. Sometimes I just do a singalong with the official music video (Batmetal Returns for Murmaider) so people have something funny to watch as well.
Also
- Bard's Song: In The Forest - Blind Guardian
But it's more of a folk song than a metal song.