NIGHT CAP

 Last drink of the night before going home (or going to bed, if you are well behaved)

e.g.

But a nightcap is different from an after-dinner drink or digestif. I stick with the classics: top-shelf whiskey, good brandy (usually Cognac), ..

www.theatlantic.com/health/...nightcap/267437/

or

Let's have a nightcap before the cops arrive.

AT YOUR BECK AND CALL

e.g


If you don't feel well by tomorrow, call me. I am at your

 beck and call.

www.usingenglish.com/.../10426

at your disposal

LOCK HORNS

e.g.

Dan and the vice president never really got along; I knew they would lock horns once they were put to work together.

or


They locked horns in the air and twirled in flight, both 

frantically beating their wings to keep them aloft. Claws

locked in combat, and spiked tails wrapped around .

https://books.google.com.br/books?id..