In case you’ve never been rafting- You can’t just sit on those big ol’ wet rubber boats.  I mean, you’re taking what amounts to a lever and shoving the big flat end into something that pushes back, and then you’re expected to propel a big heavy raft  with it.  If you don’t wedge your feet under the thwarts or into some footstraps or other wise pin yourself in that boat, you’re gonna fling yourself out now and again.  Not that such a thing can’t be fun.   It’s just that it’s more fun for the people who remain in the boat to see you fly out than it is for you to fly out yourself. And let’s face it, they’re smug enough for having kept their seats… there’s no reason for you to provide any additional entertainment for them.  So don’t make it easy for them to get you back in the raft.  Flounder and sputter a little.  Gasp and drift with the current away from the raft a bit.  Maybe pull a couple of would-be rescuers in with ya.  Make it the MOST fun for as many people as you can.