ever heard of it

no, can't say that I have.

whats the effect?

I made up something with the same name, but the effect is this


you take out the queens and jacks from the packet. you match up the jacks and queens to their suit. the jacks jump around switching positions. you place them back, only to find that the jacks have vanished and appeared on top of the deck

but u slip them in and give them a snap and then the all appear to the top ir any card the person names

Dia Vernon had a trick called jumping jacks in which a jack and an ace openly switched places, while in full view of the audience.

I learned a trick years ago called jumping jacks. You take the 4 jacks out and then put the a black jack against a red jack (put the backs together) hold each set so you have 2 red jacks facing each other and the 2 black with be "outboard". You tell a story about how the red jacks are in the shade and the blacks are out in the sun and the only way they can change is for the wind to blow. Then you blow between the 2 red jacks and magically they switch places with the black jacks. Don't know if this is the trick you were thinking of. Sort of simple and easy to do, but with practice and flair it looks pretty good.