Customers at Qdoba Mexican Grill, in the Prudential Center, can get free food on Tuesday if they don't mind a little PDA.

The nationwide chain is bringing back a Valentine's Day promotion that, according to spokeswoman Ashley Cohen, tens of thousands of customers took advantage of in 2011.

Anyone who buys an entree can get another for free—once they kiss a fellow customer at the cash register. It doesn't matter (to Qdoba) who it is.

No coupon is necessary. The promotion is happening nationwide, though in Wisconsin, inexplicably, the second entree is 50 percent off, not free.

The Qdoba is open from 10 a.m. to 9 p.m.