Enjoy this view for a moment, until you've got a little drop of pre-cum, which you will, of course, wipe on your finger and rub onto your lips.
Now, what I want you to do is wrap that shoelace around your balls.
Now tie it nice and tight.
Take the cardboard tube and cut along from one end to the other.
Slip your cock into this tube and tape it back up.
Nice and tight.