have got (one's) mind in the gutter

slang To have or give voice to lewd, inappropriate thoughts (about someone or something). He's definitely got his mind in the gutter if he thought it was okay to say something dirty like that to your mother. A: "And then she compared my model rocket to a phallus." B: "Ew, gross. She's always got her mind in the gutter." What do you expect? Johnny's a 13-year-old boy—of course he's got his mind in the gutter.