The failed Police Brutality Gambit that a random suspect tries (he bashes his forehead into a table top). Mac tells the suspect that he beat himself up for no reason.
The scene in 'Super Men' with Danny and Lindsay...Lindsay's rattling off football trivia about the vic, and Danny says it's dangerous that she knows about football because he might ask her to marry him. Jump ahead two seasons and...
Similarly, Mac and Danny's exchange in 'Until Death Do Us Part'.
Mac: It could happen to you, you know
Danny: What, marriage?
Danny: Come on, Mac, don't scare me that way.
I dare anyone to watch that now without laughing like crazy. I bet Danny never expected he'd get married in 5 years.
The episode Child's Play was a downer, but it had one very funny scene with Lindsay and Flack going back and forth being ripped off by Laughing Larry. It all culminated in an even funnier scene where Larry squirt's Flack's tie. Flack tells him "Do that again I'll have you brought in for assaulting a police officer"
"Food for Thought": At a crime scene, Lindsay complains about how hungry she is, and proceeds to recite to Danny a long list of food items that she wants. As Danny turns to walk away, he suddenly has a thought and slowly turns back to face her, wondering if Lindsay's hungry because she's pregnant again; she assures him that she isn't.
Later, Lindsay is in the lab, examining evidence from the crime scene. Danny comes to the lab entrance, dangling a paper bag containing the burger that she earlier had said that she wanted. When Lindsay tells him to bring her the burger, he reminds her that they can't have food in the lab. Lindsay then proceeds to bring Danny her findings so far, and then when Danny remarks that more lab work will be needed, she tells him that he'd better get busy, grabs the bag from him, and runs.
Danny (calling after Lindsay): Hey, wait! Come on! (waggles a finger) Save me a French fry.
The fake polygraph scene in "Damned if You Do", from Adam posing as the official administering the test to Jo counting down how fast it takes the suspect to crack and confess before Adam even starts asking questions.