Son lets mom measure his cum production

Son is a little worried because no matter how much he jerks off he keeps getting hard at the worst time and he cums like a river. He goes to his Mom for help, she says she will ask Aunt Susan who is a doctor what she thinks. When Mom gets back from the Doctor's office she tells her Son he has to cum in a cup several times a day and have it measured to see how much cum hes producing! The one catch is he needs a helper and since there is no one else around a reluctant Mom has to help!