What does “2-4-1 drinks” mean?

Please explain me the meaning of “2-4-1 drinks”.Thanks!

literally TWO (2) drinks FOR (4) the price of ONE (1) so you could buy two beers for the price of one as an example

It’s a stupid joke representation of the phrase “two for one.” Pay for one drink and they will give you two drinks. It plays on the fact that “for” and “four(4)” are pronounced the same or very similarly in most dialects of English.