Which one do you think has been the greatest blooper in films?

The first one that comes to my mind is the beginning sequence of the third Indiana Jones film The Last Crusade. Young Indy and another kid are wrestling on top of a train car with a knife. The bad kid is on top of Indy and is trying to stab him. At the same time a lantern is knocked over spilling fluid into the eye of the train's occupant, a huge rhino. The rhino reacts and pierces the roof of the train with its horn. The horn nearly nails Indy in the crotch. You can clearly see the actor, River Pheonix, say "holy sh!t!" but it's dubbed. Funny stuff.