An Astros fan tried grabbing a live ball and his companion was not pleased

If you're at the ballpark, it's important to remember some things. Among them is one simple rule: Do not interfere with balls in play. Just don't do it.
In addition disrupting the flow of the game and the likely chance of being ejected from the ballpark, you could also find yourself being reprimanded on television by your companion.
Tony Kemp hit a liner down the right-field line in the seventh inning of the Astros' 4-1 win over the Indians on Friday at Minute Maid Park. The ball was live, but a fan reached out in an attempt to corral the ball. He failed, and then this happened: 

Ouch.
After the game, Houston manager A.J. Hinch passed along some wisdom for fans in the future, as captured by MLB.com's Brian McTaggart: 

Kemp also weighed in as well:

Lesson learned ... we hope.