Green’s Dictionary of Slang

1. (Aus.) beer [the colour of ‘brown sauce’].

1900–10		Stephens & O’Brien Materials for a Dict. of Aus. Sl. [unpub. ms.] 40: KETCHUP: bush slang beer.
1941		Baker Popular Dict. Aus. Sl.

2. (US) blood [the colour of tomato ketchup].

1942		R.L. Bellem ‘Malibu Mess’ Dan Turner – Hollywood Detective Dec. 🌐 There was a red stain on my rug where Romani’s ketchup had spilled.
1950		Goldin et al. DAUL 114/2: Ketchup-dogs. Bloodhounds [...] Ketchup-hounds.
1976		(con. 1969) C.R. Anderson Grunts 64: The redder they get, the redder the ketchup flows and then they don’t say ouch any more ... red on green. ... mothers cry ... fathers ask why.
2015		67 ‘Hashtag’ 🎵 Man left the crime scene hashtag ketchup.

3. in the fig. use, the real thing.

1914

Ade ‘The New Fable of the Father Who Jumped In’ in Ade’s Fables 88: He had a Vaudeville Education and a small Tenor Voice, with the result that many a fluttering Birdie regarded him as the bona-fide Ketchup.