To TOUR, To TOUT,
to look out sharp, to be upon one's Guard. Who touts? Who looks out sharp? Tout the Culls; Eye those Folks which way they take. Do you tout and bulk, and I'll file; If you'll eye and jostlehim, I will pick his Pockets.
The Vulgar Tongue originally collected by Grose, 1811.
Also see examples in Canting Songs and Slang Rhymes collected by John S. Farmer (1896).