https://i1.wp.com/theoryofpost.com/wp-content/uploads/2017/06/use_Fotor_Fotor.jpg?w=810

Let it [the se-men] out and look at the color, white means he has eja-culated within the past 3 days, yellow means he hasn’t.
(Some people say the color will change after time too time, you can check yourself.)