have taken leave of (your) senses

old-fashioned

if you have taken leave of your senses, you are behaving in a strange or silly way.

You're leaving your family and your job to travel round the world, at your age? Have you taken leave of your senses? (often used in questions)

• When the cat's away .
• When the cat's away the mice will play.
• when the chips are down
• when the dust settles
• when the going gets rough
• when the going gets tough
• when the spirit moves
• when the spirit moves you
• when was a mere twinkle in father's eye
• when was a mere twinkle in their father's eye
• when was a twinkle in father's eye
• when was a twinkle in their father's eye
• when your ship comes in
• where is coming from
• where someone is coming from
• Where's the beef?
• Where there's a will there's a way!
• Where there's muck, there's brass.
• where there's smoke, there's fire
• whet appetite
• whether by accident or design
• whether or not
• whet someone's appetite
• which way the wind is blowing
• while away