TIL that Rembrandt's students pranked him by painting fake coins on the floor to watch him try to pick them up.

http://books.google.com/books?id=N0dVqAsR5k0C&lpg=PA45&ots=SeU8OLZUgm&dq=Houbraken%20rembrandt%20students%20paint%20floor&pg=PA45#v=onepage&q&f=false