Sometimes, I'll hear someone say "wait a moment, I'm getting a nickel," and then drop the carrier only to resume talking. Why?
"Getting a nickel" is a reference to how metered pay phones work (worked?). You'd put in some coins, make your call, and when the time you'd payed for expired, the phone operator would demand another nickel to buy more time and keep the call going.
Repeaters on automatic control typically have a "time-out" function that acts as a protection mechanism from someone or something triggering prolonged transmission, like sitting on the microphone. The repeater time-out function will then trigger and turn off transmissions for a short time before resuming normal functions.
When an amateur radio operator "grabs a nickel," they're typically letting go of the microphone long enough for the repeater to reset its timer, and then picking back up to finish their transmission.
This self-interruption keeps the repeater from turning off, and lets other parties participating on the repeater know that Chatty Cathy isn't quite yet done.
Many radios have their OWN time out timer as well, and this same mechanism may be used to reset an individual operator's radio timer as well.