Idioms

Eyes bigger than your stomach

eat more food than one can handle

Fall foul of

quarreling

Feather brain

a silly or absent-minded person

Feet of clay

hidden fault

I know it's hard to believe, but anyone you admire surely has feet of clay

Fiddle while Rome burns

concerned with trivial matters while ignoring the serious or disastrous events

Field day

an enjoyable day or circumstance

Fire and brimstone

to punish

Fit as a fiddle

in very good health

Fly into a passion

to become angry suddenly

Foam in the mouth

be very angry

Fool's paradise

a state of happiness based on a person's ignorance about potential trouble

For a song

very cheaply

For good

forever; definitively

For keeps

forever

Forty winks

take a short nap

Fuddy duddy

an old-fashioned and pompous person

Gain ground

become more popular or accepted

Gall and wormwood

hateful

Get down to brass tacks

start to consider the basic facts or practical details

Get one's feet wet

begin to participate in an activity