piss proud

(Britain, vulgar) Having an erection when waking from sleep or, more generally or metaphorically, a false or "empty" erection.

(Britain, vulgar) (by extension) Falsely proud, implying an outward display of success or virility belies a dubious reality.

(Britain, derogatory, dated) Denoting an old man who marries a young woman, implying the only erection he could muster would be prompted by the bladder.

(rare) Paruretic.