A device which is placed on the floor near a seated or
standing person, and which contains an RFID (or other)
transmitter which functions only up to a specific range,
with the partner component on the person who is the
controller of this device.
When the principal departs a room with haste,
proximity sensor of the device is de-activated.
When such an occurrence...uhm...occurs....the device fires
off, from each of several dozen small talc-containing
compressed air cannons contained therein...uhm...talc.
Each of the cannons contains both a slightly different
charge and a slightly different amount of powder, and is
angled slightly differently. Thus, for a brief moment, a
PAHF sound is accompanied by a perfectly man- or woman-
shaped cloud of dust in the air, right where the person who
hurried off was once standing.
Deluxe versions include a speaker and play cartoon running
sounds, such as "ZING," "ZZZFFFFFAAAT!" and
(tragically, inspired by a comment on Reddit).