When older couples decide to have sex, they usually describe it {to friends of the same age of course} as "nifty". Thus sex between old people is nifty sex.
70 year old Tom was telling his life long friend {Ed } of his wild night with his wife when he said smiling, "Yeah, that was really nifty sex last night."
"Dude! Did your grandpa just describe his "nifty sex" to us?"
"Yeah, I think he did because, grandma is turning red and I want to puke on my shoes....."
If you’re really good at handling the puck while playing hockey, it could have been at some point said that you have nifty mittens.
Henrik passes the puck up through the neutral zone to Pavel, Pavel corals the feed from Henrik and proceeds to enter the zone while displaying to all who are watching the nifty mittens he possesses as he dekes with the puck past two defenders at the same time and shoots the puck into the net for a goal.
Several people in the crowd say to their pals: “Did you see Pavel’s nifty mittens on that play?”.