red rider

black rider

Famine, one of the Four Horsemen of the Apocalypse.

bleed red ink

To suffer from severe net losses.

clap one's hands red

To clap or applaud intensely.

cut red tape

To reduce bureaucracy.

neither fish, flesh, nor good red herring

Synonym of neither fish nor fowl (“not easily categorized; not rightly belonging or fitting well in a given group or situation; also, not having the advantages of the various options”).

paint the town red

To party or celebrate in a rowdy, wild manner, especially in a public place.

pale rider

Death, the Grim Reaper or angel of death; and one of the Four Horsemen of the Apocalypse.

put on the red light

To advertise oneself as a prostitute.