Surprisingly enough, three in the Season 11 premier.
When the contestants found out that their first challenge would be a 5K, several contestants made comments to the camera. Justin said that he'd seen them on TV, and thought "Who'd be stupid enough to show up to one of those?"
When Arthur interrupted Bob's talking to the camera by falling over, the resulting conversation was rather amusing, and somewhat memeworthy. "How am I supposed to stand up if I can't move my leg?"
And lastly, when Jillian said something about not going to yell at people, Bob made an amusing comment about how "Jillian will always yell at people." It Makes Sense in Context.
Season 11, third week's Last Chance Workout. At one point, Arthur threw up while on the the treadmill. Jillian's comment: "Oh, he did throw up, how sweet!"