What does un marrón / menudo marrón mean?

ExpressionColoquial

a lousy job — a mess you're stuck with

An unpleasant job, or a problem it falls to you to sort out. Menudo in front is an ironic intensifier. Comerse el marrón is being the one left holding it.

Al final me comí yo el marrón.

Somebody had to.

¡Vale! for iOS

Hear it the way Spain actually says it

In the app, expressions are taught inside real conversations from Spain: read cold, explained line by line, then read again. It’s the Spanish textbooks leave out.

Unit 09

El curro

«una cosita rápida»

The ¡Vale! app: a conversation from Spain, read with its recording