mexican gap 

That patch of skin in the middle of a mustache, in the middle of the lip that doesn't grow hair.

Look at Juan's Mexican Gap, typical mustache on a Latino

mexican gap by WetBeaner March 16, 2014

The Mexican Gap 

Old Navy clothing stores. Old Navy is highly frequented by Mexican Americans due to the lower prices and relatively fashionable clothes. Do not even consider going to an Old Navy in the SW United States during any clearance sales lest you wait 4 hours to check out. You can also tell a Mexican Gap by how disorderly the clothes are arranged 30 minutes after opening, because Mexicans consider it a big flea-market where they can throw clothes on the floor they don't intend to purchase.

Friend #1: "Hey lets hit up The Mexican Gap. They have $1 flip flops this weekend."
Friend #2: "Are you crazy?! It'll be one-in-one-out because of all the Mexicans! How about we wait until next weekend, pay a little extra, and save ourselves getting stabbed by some Mexican?"
Friend#1: "Word. Or we could go to actual Gap today. There shouldn't be any there."
Friend #2: "Truth."

The Mexican Gap by Cuban_B December 6, 2009