This is it, Bob's about to get lucky. Then Alice says the dreaded words "Do you have a condom?" Bob has one, there's no need to go through the Trojan Gauntlet, instead he's faced with a greater challenge, figuring out how to put a condom on! It's a race against time, any moment now he or Alice could completely lose arousal. How does he do it? How do you get that package open? Can you naw through it with your teeth? Maybe some scissors or a paper cutter will do the trick. Once you clear that how in the name of God do you get the thing on? Does this thing come with an instruction manual! More often then not Bob fails to get it on in time, leaving him with the stretched out misused condom lying there as a flaccid reminder of his humiliating failure. This trope is almost always played for laughs. It's often used as a sign of sexual inexperience. In real life it's pretty rare, most sex ed classes explain how to put on a condom. It's actually a rather simple process.