1- An act of intercourse where the male involved seems completely switched off from the idea that the woman is meant to be getting pleasure, and instead simply gallops towards the semen depositing finale. It leaves the woman feeling like she may as well have been elsewhere. This is a priestly fuck, as one imagines that's exactly how a priest would do it- with as little extra contact as possible so as to make it less of a sin.
2- That guy who disapproves of everything you do that he can't, much like a priest does. He's the bloke who feels it necessary to make himself look better than you by reacting with disgust and incredulous disbelief when hearing of your exploits. He's a priestly fuck, that one. He probably wanks and cries over tales of his mate's debauchery.
1- "I thought you liked Tim, why did you split up?"
"Well, he was a good guy outside of the bedroom, but once we got in there, he subjected me to the most priestly fuck ever, and didn't show any interest in trying again. It's over."
2- Tom- "So I shagged them both. You only live once, right?"
(The assembled mates laugh and agree, gazing at Tom in awe. All except for one.)
Ross- "You ought to be ashamed of yourself"
(Ross gets up and goes to the bar, shaking his head and tutting. The men sit and reel in disbelief)
Tom- "Priestly Fuck!"