The ditloid "1 F in a B" stands for "1 Flea in a Bottle." Ditloids are word puzzles where numbers and letters represent a phrase or saying. In this case, it refers to a specific quantity of something (one flea) contained within a specific object (a bottle).
This is a Ditloid. The answer is 1 step forward, 2 steps back.
9 players on a baseball field
It might be "Fifty For A Bullseye" (in darts).
The ditloid "1000 B F 8" stands for "1,000 Bottles of Beer on the Wall." It's a playful reference to the popular song, where the lyrics describe a scenario involving a number of beer bottles and the act of taking one down.
1 Birthday Every Year
1 Born Every Minute
31 Ice Cream Flavors at Baskin-Robbins
b b b
1 Kelly's Eye in Bingo (bingo call)
2 rabbis enter 1 bar
The ditloid 7 equals B for S B (7 = B for S B) means:7 = Brides for Seven Brothers
b/f. reciprocal of x means 1/x, i.e. 1/f/b is b/f