[fool around] or [mess around] or [play around] or [monkey around] […]

[fool around] See: [MESS AROUND].

[fool away] or [fritter away] {v.}, {informal} To waste foolishly. * […]

[foolish] See: [PENNY WISE AND POUND FOOLISH].

[foolproof] {adj.} So constructed that not even a fool can spoil […]

[fool's paradise] See: [LIVE IN A FOOL'S PARADISE].

[fools rush in where angels fear to tread] {proverb} The idiom […]

[foot] See: [AT ONE'S FEET], [COLD FEET], [DEAD ON ONE'S FEET], […]

[foot in the door] {n. phr.}, {informal} The first step toward […]

[foot the bill] {v. phr.} To cover the expenses of; pay […]