Two Condoms....

Guy visits a latex factory, goes on a tour. They lead them into one part of the plant, the machines are going "boom sis, boom sis, boom sis.........." "That sound you hear, said the tour guide" is the machines forming baby bottle nipples, and the "sis" at the end is forming the hole in the nipple."

They go to another part of the plant, the machines are going "boom boom boom boom boom boom boom boom boom boom sis"..........and the guide says "What you are hearing is the sound of condoms being produced."

The guy asks the tour guide, "what is that 'sis' every so often?"

"That is the sound of keeping up the demand for baby bottle nipples!!!!"