jam up

Short definition from Wiktionary

Verb

1. 1
   To cause (something) to become blocked or clogged; to clog up.
2. 2
   To become blocked or clogged.
3. 3
   To cause trouble; to stop or inhibit (someone, something).

Noun

1. 1
   The situation where material becomes jammed in a machine, or some process similarly grinds to a halt.

Adjective

1. 1
   Splendid; wonderful; upstanding.