David "Dave" Grossman is a minor character in the first DLC pack for Grand Theft Auto IV, The Lost and Damned. He is first met by Johnny Klebitz in the opening the cut scene of the mission It's War.
Dave is a lawyer who in his spare time prefers to hangout with The Lost Brotherhood. Later in the game Johnny can find Dave outside of Goldberg, Ligner and Shyster as a random character. When you arrive at Dave's location, he'll tell you that his secretary is blackmailing him and accusing him of sexual harrassment. Supposedly, Dave looked at her breasts which "suppressed" her. She's currently in leagues with an attorney and they're going to bring the case to trial. Dave informs you that his wife isn't a nice person and will ruin his life if she gets wind of these shenanigans. He wants you to go and put some pressure on the secretary's attorney in the hopes of making him cease the case against Dave. Once in control, get a car (not a cycle) and go towards the lawyer's location. He'll catch on that he's being pursued and take off. Chase him down and fire some rounds into his car. Eventually, he'll give up and you're told to speak with him. Johnny informs this lawyer that the only good one in his book is a dead one, and the guy will be a really good lawyer if he doesn't give up the case. He'll agree and speed off, with the mission ending successfully.