24 year old man with artillery in his rectum: "Ooo, how did that get there? I didn't notice one going down when I was eating. I thought it was a bit uncomfortable when I tried to poop. Well thank you for sorting that out for me. I couldn't kee... No, no, ok, I guess you're right."

Older, wiser, less desperately horny men: if it doesn't have a flared base, or if there's any possibility it could come apart or break, don't put it in. Source: the internet.