Wherewear underwear, a concept designed by Theo Humphries, sends a text message to the mate of the wearer if they are removed in a location that hasn't been pre-approved. There's also Timewear, underwear that keeps track of how long they've been off, and sends a warning if they've been off for longer than a bathroom trip necessitates. Snapwear takes a photo right before they're removed by sensing the light conditions.
These are just concepts (and obviously conceived with a lot of humor, watch the videos) but should someone make these for real one day, and you are tempted to outfit your partner with a pair, or they give you a set for your birthday, dump them and RUN.
From sexblo.gs.