REWARDS - Respect
You'll see Tenpenny and Pulaski exit Smoke's house and Smoke is a bit agitated since they keep bothering him. Smoke mentions that his cousin is coming in from Mexico and he wants you to come with him. Get into Smoke's car and drive to the yellow blip on your radar. Smoke mentions his "cousin Mary" is inside and you realize he is talking about marijuana.
After a short and insulting conversation with two Mexicans, they start walking away and Smoke sneaks behind them and smacks one in the head with a bat. The other one starts running off and it's your job to run him down and kill. He will appear as a red blip on the radar. Use your Super Sprint to catch up to him and kill him, which marks the mission as complete.