Where someone acts arrogantly/annoyingly "pious 'n' preachy" ("I'm as honorable as a parson!") when publicly interacting with others, but is in reality a totally selfish/dishonest jerk in his private actions.
I somehow can never develop much respect for some highfalutin nose-in-the-air who claims to be a religious fanatic, but who also cannot appropriately handle even a simple moral-question situation --- talk about a split parsonality!
Mary exhibits split menu personality syndrome as she places her drive-thru order, "Umm yes I'd like a Number 3 Value meal, super-sized with a small diet coke...oh yeah and add in an apple turnover"