Green’s Dictionary of Slang

rooter-tooter n.

[rhy. sl. fruiter n.]

(N.Z.) a male homosexual.

[NZ]W. Ings ‘Trolling the Beat to Working the Soob’ in Int’l Jrnl Lexicog. 23:1 60: Rhyming slang dates from circa 1840 [...] For example, tea leafing (thieving), rooter tooter (fruiter/homosexual).