The expression tomar a cerveja na bundinha can be translated as "to drink the beer by its bottom" or, more literally, "to take the beer in the little ass". It is a challenge for certain young Brazilians to say the expression without giggling; in fact, the drink is probably propagated mainly for the opportunity to ambiguously suggest beer enemas.
Is it tasty? As we've mentioned before, Brazilian beer is terrible, so adding some saltiness and the acidity of the lime can't help but be an improvement. Tipsy Pilgrim recommends it.
To make your own cerveja na bundinha, follow these steps:
1. Turn the can upside down. With a heavy-duty knife, puncture a hole in the middle of the can's ass.
2. Puncture a second hole near the rim of the underside. This will be your drinking hole.
3. Pour coarse salt over the can's ass, then squeeze lime over it.
If you need to see the process, some rather drunk, sarcastic boys have made a how-to video (in Portuguese).