Sort of - only the light version (a sigmoidoscopy.) They don't give you either sedatives or anesthesia the way they often will when it's going around the bend of the colon, and while it's unpleasant (and embarassing, although I lucked out and the doctor (or nurse/tech?) who administered it looked like she'd be someone's grandmother, and was about as reassuring and non-embarassing a witness as one could ask for), it's not painful.

For that matter, there's plenty of pornography out there demonstrating just how large an object can go there given a willing recipient. I don't recommend looking for it, though.

I have to assume that's more a matter of a lack of a willing bomber, or the organizations involved having access to more effective and less costly methods.

I'm of the opinion that one could quite readily go to the lavatory on the aircraft, or even in a bathroom stall in the airport post-security, without other passengers noticing anything out of the ordinary except some uncomfortable noises indicative of say, traveller's trots or motion sickness or bulimia.

On-aircraft, I'd certainly hope that bringing a full-size carryon into the restroom would attract attention, but in the airport it would not, and on-aircraft you could quite readily bring in a toiletry kit, dump the original contents and put the device in to return it to your seat (or just detonate it in the lavatory if it's on the outside of the plane.)

Given that we've been paranoid about items that would fit into a normal shoe or someone's underwear, the volume when dealing with solids can't be that large or the threat involved with the prior two failed attempts can't have been as big as previously believed.

Fortunately, both of those two attempts seem to have been epic fails on the terrorists part, and foiled because of some combination of passenger vigilance and their own incompetence, with the TSA rather late to the party on those threats.