Hey sweetie! You've grown into such a wonderful young man, and I just wanted to tell you how proud I am of you. I also noticed that you've been spending a little more time alone lately, with the door locked. Mommy knows what guys your age do behind closed doors... don't worry, you're not in trouble! Masturbating is completely normal. I just want to make sure you're healthy. So today, Mommy's going to have you take your cock out and stroke it for her, so we can see how much cum you have when you ejaculate. Don't be shy, sweetie, it's okay to have feelings like this and it's okay to touch yourself. Here, why don't I help you out a little? First I open up my sweater, teasing you a little more with my big BBW body. But we need to get a very accurate sample of how much cum you have, so Mommy decides to help you out by taking out her huge tits for you to stroke to! Now be a good boy and work up the biggest load you have for your Mommy's big breasts.