Green’s Dictionary of Slang

plabbery adj.

[Irish plab, a person who is easily taken in]

(Irish) foolish.

[Ire]Joyce Ulysses 695: Id just go to her and ask her do you love him and look her square in the eyes she couldnt fool me but he might imagine he was and make a declaration in his plabbery kind of manner to her like he did to me though I had the devils own job to get it out of him.