In Mexico City they searched everyone's bags thoroughly, not once but twice, for a flight MEX-IAD on UA. First time was at check-in, second time all carry-ons were searched at the gate, and we were all wanded (even after going through the metal detectors earlier.)

What was rather humorous, though were the items that we had to remove from carry-ons and put into checked bags:

1. thread (not needles, mind you, but spools of sewing thread)

2. pencils (what are we supposed to write with on the plane?)

3. tweezers (huh??)