cop a buzz:  to feel the effects of taking illegal drugs or drinking alcohol
cop off:  to meet someone and start a sexual relationship with them
cop off with: to meet someone and start a sexual relationship with them

The hero eventually cops off with the princess.

I don't recall having heard the sentences above.  This doesn't mean that someone, somewhere, some time has not said them, but I'm not familiar with those uses of "cop".  

This is one of the problems associated with learning words out of a book without context instead of hearing or reading the words in context.  (We've all done it.)  Does 1% of the population use them?  Or is it 10%?  What is the advantage of learning words that only a small percentage of the population uses?  Was the expression widely used forty years ago but is now considered out of date?  (I often find out of date American slang in books published for foreign students of English.)  What is the advantage of learning words that are considered out of date or perhaps unique to a certain region of a country?  If you are living in that region or associating with people from that region, great.  If you're not, maybe your energies should be directed elsewhere.  Let's say that "to cop a buzz" is up to date slang.  Who is going to be using it?  Can we say it would be expected to be found in the vocabulary of users of controlled substances and/or alcoholics?  Just how many substance abusers are you communicating with in an average day?  A week? A day?  How necessary is this knowledge?

I'm not trying to give you a hard time, but I think you're spinning your wheels (wasting your time).  But it's your time, right?