I think we're beyond euphemisms at this point: God's a Skee-Ball fanatic.
Okay, but what if he LIKES IT when people call him Cas?
"Only my DAD calls me Castiel, you guys! That is, if I was sure my Dad existed and wasn't out playing skeeball on the Jersey shore or something instead of intervening to stop the war between heaven and hell. What was I saying? Oooh, nice shoes, Dean."
"... Dean's still unconscious. And those are hospital slippers, Castiel."
"Cassssss..."
Off to plan mischief!