Your question appears to presume your own definition of "100% straight" which in and of itself has been a question of some debate here.
The scenario you pose, as I read it, has the subtext "Would you recant your self-proclaimed inflexible sexuality in exchange for a shiny, pretty fuckbaubble if the opportunity presented itself?" or, more succinctly, "Are you a liar or are you just weak?"
That presupposed that everyone says they're straight (and who is truthful about it) for the same reason. There are those who say they are 100% straight because the idea of gay sex is repulsive and disgusting to them. There are others who say they're 100% straight because they have no attraction to men without being repulsed by the idea; simply that love/lust "click" doesn't happen. And of course every shade in between.
So you appear to be asking "Would you do this gross, disgusting thing to get this wonderful, splendid thing?" (so that you can judge them for it) when for some of your audience the question is interpreted as "Would you do this thing to which you're relatively apathetic about to get this wonderful, splendid thing?"
Why not just ask the question "What do you consider "straight" to be?" Or better yet, read the dozens of threads already on here.