Britney Spears -- Taco Muncher

Screw the border, Britney Spears was runnin' for a taco stand outside the set of "How I Met Your Mother" yesterday!

TMZ spies spotted Brit on the FOX lot, waiting in line like everybody else, during a break in production. Ever the elusive creature, Britwreck took her food to go before our mole could whip out his camera phone.