Refers to one being incredibly muscular or 'Jacked'. It could also refer to someone showing off their muscles, either needlessly (Walking around town shirtless on a summer day), or unintentionally (At the beach).
Example 1:

Bob: Hey Leroy, look at that dude walking down the street. Why the hell does he have his shirt off?

Leroy: I don't know. I bet he thinks he's a total Jack Show or something.

Bob: What an idiot!

Example 2:

I've been working out straight for about a year and I'm pretty sure I went from a tiny wimp to a complete Jack Show.
by Mpk101 January 21, 2009
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