Green’s Dictionary of Slang

to wash oneself (in a bath or tub).

1610		Jonson Alchemist IV i: In your bathada, You shall be soked, and stroked, and tubb’d, and rubb’d, And scrubb’d, and fubb’d, dear don.
1883		Illus. London News 27 Jan. 87/3: To ‘tub’ for to bathe is [...] Society slang (generally and university).
1885		Bulletin (Sydney) 9 May 12/1: One thing is certain – that if the alderman don’t tub until their drought has subsided, not a man Jack of them will ablute till the Day of Judgment.
1890		Bird o’ Freedom 1 Jan. 1/1: People who live in glass houses should have curtains — especially when they are tubbing.
1927		W.R. Morse ‘Stanford Expressions’ in AS II:6 278: tub — plunge into a tub of cold water.
1929		Bulletin 13 Nov. (Red Page) 5: Why any nation would pride itself on being ‘well tubbed’ is a mystery.
1974		D. Ireland Burn 123: The smell of her. Dark. Just won’t tub.
1990		Tupper & Wortley Aus. Prison Sl. Gloss. 🌐 Tub. To shower or bathe. As in ‘to have a tub.’.