Yes, they have even been known to eat threads here on the board.
I’m finding a lot of references on the net saying 'Hippos kill more people than any other wild animal", that doesn’t make it true, of course, but they are terribly powerful animals…
duplicate thread; the one where the OP was sucessful in posting is here:
http://boards.straightdope.com/sdmb/showthread.php?threadid=120901