rootin' tootin' · adjective1
Possibly from rooty-toot (“something loudly exciting, boisterous, or riotous”, noun) (chiefly US, slang), from rooty-toot (“to make a tooting sound; to act in a jaunty or lively manner”, verb), ultimately imitative of a trumpet’s sound, perhaps also influenced by toot (“to go on a drinking binge or spree”) (US, slang), or tootin', tooting (intensifying adjective) (US, slang).
rootin' tootin' · adjective2
Probably from rooting (“of a pig: that digs or turns up with its snout; that rummages or searches”, adjective), reduplicated with a change of the initial consonant; compare also toot (“to see; to spy”).
Etymology from Wiktionary, CC BY-SA 4.0.