Also, a single cherry is the norm, perched decoratively atop the whipped cream. So “86 the cherry” would have been clear, and they could maybe get away with “86 cherry” according to you, but “86 cherries” might as well be “69 cherries.” You wouldn’t expect that to mean mutual oral sex.
Mileage varies. I’ve seen “86 [thing]” written on whiteboards more often than not, grammatically speaking.
Also, a single cherry is the norm, perched decoratively atop the whipped cream. So “86 the cherry” would have been clear, and they could maybe get away with “86 cherry” according to you, but “86 cherries” might as well be “69 cherries.” You wouldn’t expect that to mean mutual oral sex.