Boyfreinds Jokes

One day i was out looking for a Birthday present for my sisters 19th birthday and as i was walking down the card isle and spotted something that looked like it would be good....But before i tell you the joke you need to know that my all of my sisters x boyfreinds have either been in jail or are on their way to jail so back to the card....
On the front it said
Hey Sis i was going to get all of your x boyfreinds to sign this card for you... then when you opened it up it said However the guards wouldnt let them have any sharp objects!!!