The initial idioms of the letter F

flash through mind	flash up
flashback	flasher
flat	flat as a board
flat as a pancake	flat broke
flat chat	flat-earther
flat footed	flat on ass
flat on back	flat on one’s ass
flat on one's back	flat out
flat out like a lizard drinking	flat strap
flat-ass	flatfoot
flat-hatting	Flathead
flatheaded	flatline
flatten out	flatten
flatter	flatter (oneself)
flatter figure	flatter oneself