I don't mean to be alarmist, but a girlfriend of a friend of mine was actually subjected to a body cavity search at a US airport last week. She had not set off a metal detector, nor did she or her luggage test positive for any explosives or drugs. She has no criminal record.

The reasons for the search were much less concrete than that. She us a US citizen who was born abroad (to US parents, so she's always been a US citizen). She had presented her US passport as ID for a domestic flight instead of a driver's license. Her mother changed their last names when she divorced her father. She had purchased a one-way ticket.

It should be noted that they found nothing in any of her body cavities, and was allowed to board a flight.