Denny's is an American table service diner-style restaurant chain. It operates over 1,600 restaurants worldwide and is now known for always being open and serving breakfast, lunch, and dinner around the clock.
In "Road to Europe", after Lois embarrasses herself and Peter at KISS Stock, they find KISS having breakfast at Denny's where Peter finds that she once had a relationship with Gene Simmons, redeeming her in his eyes.
While pretending to call plays during a backyard football game in "Bri-Da", Joe points out that Peter's play sheet is really a Denny's menu. Peter brushes this off but the play he calls is 'Moons over My Hammy.'