Your favourite idiom?

[RHCP_fan]

Yellow, guys!

Everybody has a favourite word in a language.
I was wondering: what's your favourite idiom, if you have one?

As for me, it's "cupboard love" ^^
I know the meaning is fairly negative, though I just love it :)

Go on, express your love to idioms! ;)

[Over the top]

out of the blue is my favourite. It means suddenly or unexpectedly.
I learnt it from a song called Out of the blue by Delta Goodrem.

[TheJoker]

have a (good) head on one's shoulders

to be sensible and intelligent

[Hiccup]

I love idioms (and still learning) and cannot just pick one.

I find idioms a very creative way (visualizing) to put the meaning across.

[mara_ce]

till the cows come home: for a very long time; indefinitely
burn the midnight oil: to work or study very late at night
head over heels in love: deeply in love
let bygones be bygones: forget about the disagreement