You'll pay with bumsex.
I've never heard Con-Dem tax policy so succinctly explained.
Although it is more the feel of the policy:
Had quite a few crazy bedtime moments but none will ever compare to me being asked to feltch a womans arse...........and not something i was going to do much to her annoyance.
Thanks for sharing. 
Felching was always one of those things we knew was dirty as kids but never quite knew what it was (along with I believe frotting, which is no way near as bad). Young 'uns have it so easy these days with the Interweb allowing them to look up random and degrading filth in seconds. Rather ruins the search and mystery The Internet also made the Porn Fairy extinct too.
On topic: I'd imagine that if you wanted to push the envelope in such a manner then you might need to see how the ground lies beforehand and I also think it'd be unreasonable to be annoyed if someone wasn't up for it, it is rather a... specialist request after all. You might be able to negotiate an impromptu rimming, as long as everything was presentable back there, but a surprise finger up the jacksie might not make you many friends (although anecdotal evidence suggests the bolder young lady may still give it a shot). Although everyone will draw a different line in the sand and I suspect it is a similar conversation in the pub recently that brought up the topic of anal douches - so it pays to be prepared too.
