Term used to describe someone you once dated, who unlike you, cannot let go. So they "pop-up" randomly in places they know you frequent as such: Your favorite book store, the park where you go jogging, the mid-night movie at the theater near your house - even though they live at least an hour away.

An individual demonstrating Jack-in-the-box tendencies can quickly become a Stalker or a full blown Psychopath if not confronted with the Jack-in-the-box behavior.
Smitty and Jane break-up. Smitty, in a fit of anguish tells Jane he is leaving the country and never coming back.

Later that week....

Jane is jogging along her favorite running trail, rounds the bend and there Smitty is running toward her with a shit eating grin..."Oh Jane! I wasn't expecting to see you here!?!?" Smitty has pulled a classic Jack-in-the-Box.
by Sophacles September 26, 2012
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A fine fast food restaurant with a large variety of burgers, unique fries, as well as many other unique edibles. They don't make it til you order it.
by Wild Bill August 3, 2003
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A toy. Not to be confused with "Jack in the box", a fast-food restaurant.
Baby Hugo cried whenever he played with his Jack-In-A-Box. Every time Jack popped out it frightened him. Bad Jack!
by MTF January 22, 2009
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When you have an erection that your girlfriend doesn't know about and you whip it out of your pants and show her your hard on, usually with a really pleased expression on your face.
I was lying in bed reading the other day when Rob pulled down the sheets and sprung his jack in a box on me!
by Robertion August 17, 2011
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Fast food resturant popular in the US, and HOLY in California. With such a wide selection of supreme quality food at such affordable prices, Jack in the Box rules all other fast-food franchises worldwide.
I'm hungry and only have a little money. I KNOW! I'll go to Jack in the Box, get full and have a lot of cash left over!

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by Evil Pumpkin December 11, 2003
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When a girls fists herself and then you put your dick in too and she gives you a handy.
I went to a donkey show in Tijuana and the girl really stepped up her game by giving the bachelor a Jack In A Box.
by fucklayton August 16, 2015
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One of the best fast food restraunts out there. An actual clean restraunt other than hardees or mcdonalds. They make quality food.
Im gonna get me a chicken fajita pita from jack in the box.
by Oz April 20, 2005
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