Irish rocker Bono has learned to watch his cash more closely, after losing a small fortune during a shopping trip.

The U2 frontman and his good pal, rapper Dr Dre, were shopping at the upscale PRADA store in Aspen, Colorado, and were leaving the store when a deliveryman noticed a wad of $50 bills on the floor and asked if anyone had dropped it.

The U2 singer checked his wallet said, "I did."

But instead of walking out with the whole bundle, Bono generously peeled off two of the notes and handed them to the honest stranger.