"Lordy, I Hope There Are Tapes!"
"Hold My Beer..." -- Michael Cohen
= new reply since forum marked as read
I believe Comey could have known about the tapes when he said this. (maybe?)
Nobody uses tape any more. 
Kind of like saying "footage" when referring to video.
Oh well, many idioms like this seem to survive over time. 
Cheeto accused Comey of lying about the meeting where he demanded loyalty. Cheeto said "You'd better hope I don't have tapes of that meeting."
Comey's answer was, "Lordy I hope there are tapes!" Because of course he realized that any recording of the meeting would prove that his version was correct. Cheeto never did produce any "tape" because, why would he?
It's conceivable that there are a treasure trove of recorded phone calls that SC Meuller has in his possession and not just from Cohen's office.
There could be hundreds of recorded tRump phone calls of him saying a lot of awful, conspiratorial and/or illegal things.
Most newer VOIP phone systems have the phone recording feature built in: date, time, WAV file recording. It's all logged, mostly so that callers cannot say they didn't say something over the phone. A legal or Real Estate office or financial institution would be advised to use such phone capabilities. Our VOIP system does that. Would you like to hear what I said a week ago during some random conversation? Every phone call is there and I cannot delete any of them.
The phone recordings are usually stored for some time. Cohen wouldn't necessarily need to do anything or get involved, it would just be something his phone system would do as a normal course of business. And the FBI would know to pull those recordings and phone logs. No question about it!
Imagine the possibilities. 
