How do I get a seriously dirty DVD back from my partner's parents before they see it?

In a drunken haze I was utterly convinced that my partner is so good in bed that her parents would be so proud they should know about it. So I sent a home video to them in the post and now I've sobered up I realise the trouble I'm in. How can I try to get it back before they see it? There's some really depraved stuff on there...