Daycare manager found this on one of the closets after a remodel. No one has a clue...

I don't know, but I'd be very, very nervous if someone approached me holding that.

What does the end of that cable look like? Can you get a photo if it facing the other way?

Something Darth Vader used.It will be interesting to know the answer.I think a photo of the end of the plug will give the clue.

Looks like some kind of high voltage probe.

The connector is a PL-259.
Looks like an "arc" will be produced between the electrode probes.
Shock therapy device most likely.

Looks something like a moisture meter probe to check moisture content of lumber.

Daycare operators use them on both severely congested and runny nose kids.

Depending on which condition, you either hook it to AC or DCEP on a small welder and stuff half of the probe up each side of the kid's nose.  Step on the footpedal a time or two and the rugrat is cured.

home made Cattle Prod?

After looking at the connector I would guess that is for testing coax cable used for connecting TVs an such tp the roof antenna  or cable box -- to test the cable for proper installation of the end connectors. (Just a guess) Basically it's a continuity tester.