I am wearing a butt plug since 9 hours, I think it is the longest I have done it.
I took an airplane in St-Petersburg, with the plug in my hand luggage to pass the customs because I thought they could have a body scanner, which was not the case.
I don't know if it was related but when my bag passed the girl checking the x-ray was laughing with a colleague...
So I put the plug in the toilets and took the plane until Amsterdam where I had to pass the custom another time to take my second flight... and this time they had a scanner, oops !
I was a bit scared but fortunately it was not a problem. I've just checked and it only detects objects on the body and not in it, I was lucky !
It is this plug, very comfortable and totally invisible: