To paint the town red

to go out and celebrate; to go on a drinking bout; to get drunk. - Faire la bringue

• They were out painting the town red last night.

Origin

The expression is American slang meaning to go on a reckless debauch, to be wildly extravagant. Originally, the metaphor applied to bonfires painting the sky or scenery red. An old Irish ballad contains the lines: The beacon hills were painted red/ With many a fire that night. 

The immediate source of the phrase may be traced to the times when a Mississippi steamboat captain would want to defeat his rival. `Paint her, boys!' he would command his men as they heaped fuel upon the fires at night, casting a red glare upon the surrounding scenery. The phrase was helped into popularity by the fact that `to paint' (ie to paint the nose red) was an old slang term for drinking. [Source: Handybook of Literary Curiosities, by William S Walsh (Lippincott 1892).]
Peter Whitehead, Shaw Heath