The Blue Movie

My friend jumps across the room to take out the DVD and sprints up the stairs. His parents come in and find me trying to change the channel. My friend panics at this point and says, I forgot to flush the chain. But if you want, you can go and look in the toilet and you can see my urine. And we all then sit down but everyone knows something is going on. So we're watching the TV now. And his dad says, what's this you're watching? And only at this point, I realized we're watching a program about gardening. Then luckily, his dad decided to put us out of our misery and said, where's the blue movie