In last Sunday's game against the Cardinals, Brent Celek and Riley Cooper high 5'd (or low 5'd, or medium 5'd, or whatever) on their crossing route. Celek caught a TD pass on the play. You can see video of it here, but here's a screenshot:

When asked why they high 5 as they pass each each, Celek explained that he's just saying "Good luck on the other side, bro."