The phrase that someone uses when they're never going to tell you shit.
Friend 1: Hey, are you free this week?

Friend 2: I'll let you know.

*Never talk to each other again.*
by Brownie72 December 22, 2011
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something you say after a lame excuse to cancel plans with friends, usually for a better offer, without any real intention of considering original plan
a guy you've been dying to go out with asks you to dinner Friday night:

Sorry Rachel - I won't be able to make it to your sister's middle school graduation Friday night - will need to work late that day but if anything changes I'll let you know.
by smores21 July 15, 2012
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