Smash Mouth -- Singer Rages Out ... Over Bread?! (TMZ TV)

The lead singer of 90s band Smash Mouth lost his mind when fans decided to throw sliced bread on the stage -- and just as Steve Harwell started threatening the audience, the band started cranking out “All Star.” Absolute perfect timing!

That is ... if you ever wanted to get cursed out by an aging rocker while his hit song played in the background.