Shly (Adj): To be ridiculously slimy, oily, or otherwise greasy, while at the same time being very sly. The y sound can be accentuated, "Shlyyyyy".
"Sir, may I be excused from the lesson, I have an appointment with my....dental proffessional."
"What a shly dog."
"Apologies, my table tennis tournament, the TTTT, has had to be...terminated. There will be no refunds."
"Hisssssssssssss, shly! Shly!"
Incredibly sly- likely to steal your money, double-cross you, or lie to you- pronounced slowly.
What do you mean you won't gimme the ticket, I already paid...Alex, you're very shly.