It requires unparalleled courage to set the Thames on fire.

To get cold feet

Harassed by repeated acts of injustice, he decided to <u><em>put his foot down</em></u>.

To catch somebody on the hop

To be at loggerheads

To see red

It is time that professors came down from their <u><em>ivory towers</em></u> and studied the rea…

To smell a rat

He is <u><em>at loggerheads</em></u> with his assistants about the management of the concern.