Green’s Dictionary of Slang

passionate, obsessive.

1920		F.S. Fitzgerald This Side of Paradise in Bodley Head Scott Fitzgerald III (1960) 54: That isn’t as pash as some of them.
1924		P. Marks Plastic Age 24: Gloria Nielsen is there, and she’s a pash baby.
1929		W. Winchell On Broadway 6 Sept. [synd. col.] Rudsy Valentino, the greatest of the Pash Princes, Sheiks, Stage Idols and ‘It’ men.