"Bevakasha" is the common Hebrew polite answering form to "thank you"
Mr. Cohen has lived some time in Israel and even lived in a Kibbutz for a while.
In the earlier days he was quoted that he always thought bevakasha was a cool word so he thought he'll use it.
Some claims that boyakasha is derived from the Hebrew term "Beitza Kasha" that means "boiled egg"
- Bevakasha (you're welcome) =>> Boyakasha