Hi there, thought I would reply to your post, I am a purely hetro straight male, married to a gorgeous lady and we have quite a selection of her toys to play with, Wi-vibe 3, magic wand + attachments etc etc, but I have a little secret she doesn't know about... I am obsessed with playing with my bum when i am masturbating, always have since I was a teenager..
I have put most things up my bum over the last 30 or so years, from fingers, bananas, cucumbers, vibros, anything really that left me with a nice snug full feeling. I just bought myself the european lover 9 inch and the basics 7 inch extra girthy realistic dildos and they are both good in their own way.
the 9 inch one gets deep enough to push my sweet spot and is soft enough to not hurt, but it could do with being a bit fatter for me hence the 7 inch one i got as well. The only problem with the thick one is it isn't quite long enough for me. with the testicles at the base you can only get so much in, still, once there it does fill me up nicely.
like everybody above says, prep yourself first. I find a nice warm flush out with water not only gets rid of the annoying side effect of playing with your bum, but use a decent lube as well. I have tried everything from vaseline, KY, saliva, butter, sudacrem, savalon, baby oil etc. The durex play range is nice, the tingle one has an interesting sensation when you first start..