light a fire under (someone)

mainly American

to make someone work better or harder.

It's time you lit a fire under those guys or they'll never finish painting the house.

• knock the bottom out of
• knock the bottom out of something
• knock the daylights out of
• knock the daylights out of someone
• knock the living daylights out of
• knock the living daylights out of someone
• knock them dead
• knock the stuffing out of
• knock the stuffing out of someone
• knock the tar out of
• knock the tar out of someone
• knock up
• knock wood
• knock yourself out
• knock your socks off
• know-all
• know a thing or two
• know backwards
• know backwards and forwards
• know beans about
• know beans about something
• know best
• know better
• know better than to
• know better than to do something