I did once.
Whilst at university I really fancied this German girl. She was definitely into the whole environment thing and volunteered to help copice some woods on the south downs. Seeing an opportunity, I volunteered as well.
My reckoning was that we'd spend the day together, have a shared experience, it'd make me look good (I wore my Levellers t-shirt as well, since I knew she was a really big fan of the Levellers), and that I'd get my wicked way.
It was hard work, but I must say it was enjoyable as well.
But my dastardly scheme came to nothing - never did manage to cop-off with her.
That did teach me a very important lesson though: don't bother volunteering again - it's not worth it.
Not really (well, I really did volunteer with the hope of impressing her, and I really didn't get anywhere. But that's not the lesson I learnt).