The trick is NOT take these waves standing up. Just like surfers diving under waves as they are paddling out, you dive low into the bottom of the wave and let it pass over you. You do that, and its no problem.
If you stand up and let it hit you, it can feel like a car accident. Alot of the injuries occur when you do that, and then the wave sucks you up to the top and drops you back down. We call it "going over the falls". I've seen people drop head first from a top of a large wave onto a waterless patch of sand by this because the waves crest right at the edge of the beach. Many had to be taken away in an ambulance.
Also seen plenty of males and females get their surfshorts/bikinis literally ripped off their bodies from the force of "going over the falls". Always amusing, and sad, when you see some poor soul dragging themselves out of the water and doing the birthday suit thing.
The opening scene in Disney's "Lilo and Stitch" shows Lilo doing something like that when she rides a large wave onto the beach.
See 00:53 of this clip:
http://www.youtube.com/watch?v=xVptV_Da5qw
I'm sure Disney had some good Hawaiian surfing consultants for that movie!
Gives a whole new meaning to the phrase, "go pound sand".