catch a falling knife

bring a knife to a gunfight

To enter into a confrontation or other challenging situation without being adequately equipped or prepared.

catch a body

to kill, to murder

catch a break

To experience the minimal amount of good luck or a favorable outcome.

catch a case

To be infected with a disease; used with of.

catch a cold

To contract a cold.

catch a date

Of a prostitute, to secure a client who is willing to pay for services.

catch a fade

To get knocked out (struck and rendered unconscious).

catch a packet

To be fired upon.