If Murray reaches QFs I will never watch clay tennis again
It would be better if you could make a bet you could prove like, say, changing your sig to "I love Murray", donating your vcash to a known Murray fan, posting a pic of yourself in your undies or whatnot.
I'll make a different variation... If someone manages to beat Nadal in RG, I'll change my profile pic to one featuring uncle Toni until the ATP world tour finals. I can promise that because I know it won't happen