Brent Celek explains why he high 5's Riley Cooper on crossing patterns

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."