definitely ask him and take the risk, you've been together for 20 years i would of thought you would of shocked him more in those 20 years, than saying you have a fantasy about chris tarrant, and you will always be fantasising otherwise and that's what your partners there for, the mind boggles though i just think chris tarrant" who wants to be a millionaire",so shall we go 50/50, ask the audience or PHONE A FRIEND, ummm that one could be a wrong idea, or BUT WE DONT WANT TO GIVE YOU THAT(am i getting warmer), or Tizwaz(buckets of custard come to mind) only teasing its your choice but i say go for it, even if it does involve the yellow stuff, sounds quite fun actually.
GO FOR IT.