Bam Margera, from the MTV show Jackass, had to undergo emergency surgery a while back after performing a stunt in a kayak.

TMZ obtained footage of the stunt where Bam was teamed with a professional in a tandem kayak where the two went over a waterfall and plunged into the stream over 100 ft. below.  The stunt took place at an Oregon waterfall last week and one of the last things the professional tells him it to tense everything.

The pair go over the waterfall and Bam gets ejected from the boat on impact and comes up beside the boat.  Because the impact was so intense he suffered damage to his abdominal wall and had to have emergency surgery to correct it.

After getting to the shore and catching his breath, Bam said, "No. 1, that was the most gnarliest thing I've ever done!"

What's the most daring thing you've ever done?

Check out the video of the stunt below.