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1.
derived from the word cock
also see willy,dong,shlong, and sausage
"gee mister, thats a mighty large cyack"
or
"HEY BITCH! suck my cyack"
by Juie Stain December 09, 2003
 
2.
A slang term for cock. It sounds better, and more emphasis can be put on the syllables.
"Cyyyyyyyyyyyyyyyyack!" (Pronounced K-eeeeeeeeeeee-yak)
"Oh my Cyack!"
"What the Cyack?"
"Holy Cyack!"
"Cyack?!"
by Liam Gilbertson August 19, 2007