Charlie Sheen Foots the Bill

If you take care of Charlie Sheen's feet, he'll take care of you.

Our spa spies tell us Sheen dropped by to get his little piggies a pedicure -- and when all was said and done he dropped a $100 tip on a $50 bill. We're told he was "one of the nicest clients ever."

Considering he reportedly makes $800,000 an episode for "Two and Half Men" ... he's probably one of the richest too.