I asked my boy whether he was interested in trying this out, because he likes him bum to be played with, but his answer straight out was 'no'. I thought it might be nice because then I could penetrate him deeply, rather than just with a finger, or a vibrator.
It seems that guys who are straight still have tiny little hangups about being 'gay'... I think the idea of a girl taking them is nice, until something that looks like a penis is involved.
Edit/Addition by MJ's boy: (re strapon's) it's less a fear of being 'gay' and more just that it'd not get me going. However, a vibrator in that area (WITH penetration) is so very nice, but strap ons are just... not as arousing? ....given a little coaxing, I'd do it if she asked to. Mightn't get me off, but if she enjoys it, why not?