take it into (your) head to (do something)

to decide to do something.

Uncle Julian might take it into his head to say almost anything.

Usage notes: usually said about doing something silly or surprising

• the mind boggles.
• the minute
• the minute back is turned
• the minute someone's back is turned
• the minute that
• the missionary position
• the moment of truth
• the more one thing happens the more
• the more one thing happens the more another thing happens
• the more the merrier
• the more the merrier.
• the more the more
• the more the more another thing happens
• the morning after
• the morning after the night before
• the mother from hell
• the mother of all
• the mother of all something
• the mot juste
• the movers and shakers
• the moving spirit
• then again
• the name of the game
• then and there
• the nature of the beast