"to speak of the devil"
the person who you were talking about unexpectedly arrives
"to cost an arm and a leg"
something very expensive
"to get cold feet"
to suddenly change your mind about something because you are nervous
"to ring a bell"
soemthing that sounds familiar
"to bite the bullet"
to make yourself do something difficult or unpleasant
"take the plunge"
to commit to a decision (usually one that makes you nervous)
"once in a blue moon"
rarely
"give the green light"
to allow something
"to be on the ball"
to be alert
"to pull someone's leg"
to fool someone
"to beat around the bush"
to avoid talking about something
"to be under the weather"
to be ill or sick
