A screenshot will be coming when the event decides to happen again. Obviously, because I mentioned the diaper event to you, it stopped happening all the time.

However, I did find a couple mentions of the event in the forums, but I'm not sure what type of crate it was.

This post seems to indicate that it is a well-packed crate that brings them about. But again, if the event ever decides to rear its head again, I'll send you a screenshot.