ROFL. I find that propping my bum up and staying as still as possible for a while helps. Still get a bit of leakage though, but I read that it only takes the a very short time (10-15mins or so) to swim up through the cervix and then most of what leaks out is just the semen (rather than the actual little swimmers themselves IYKWIM).

I have read that quite a few women in the US use special 'cups' originally designed for use during AF. I think they are a bit like a diaphragm or something and they can be either inserted after to try and hold everything in, or DH does his thing straight into the cup and it's then inserted. Interesting stuff!