Iain points to this gem of an article. Some choice quotes:

Dr Greening and colleagues asked 42 men to ejaculate every day for seven days Excuse me Sir. Yes, sorry to interrupt – would you mind doing me a favor? Yes, I just need you to jerk off every day for a week. … Say, how’d I wind up in hospital again?

I think it’s exciting Don’t we all Dr Greening. Don’t we all.