Wasn't the whole theory of the Trojan horse to sneak into the fort then jump out and attack?
Given this theory, why would they call condoms Trojans?
I gave your query a lot of thought just now. I really pushed the limits of my knowledge and gave it everything I had. I thrust my wit to and fro with great rigor. To be honest, I even found myself on my back for a while, and I was really being ridden hard. And I have an answer for you:
Premise 1: The Trojans were devoted primarily to Apollo.
Premise 2: Apollo is a sun god.
Premise 3: Vaginas and other penetrable orifices are very dark.
Premise 4: A god of the sun is powerless in a dark place.
Premise 5: A god's followers are powerless without the aid of their god.
Premise 6: The Trojan Horse was not in fact Trojan, it was built by the Greeks in order to despoil the Trojans.
Premise 7: The Trojans were basically crybabies
Premise 8: Crybabies never win
Conclusion: Trojan condoms are effective because they are ineffective at being effective! For you see, a true Trojan Horse would be rendered powerless by its own crybabydom and the pansytude of its god in the dark recesses of the feminine parts. This means that Trojan Condoms are in fact designed to fail at penetration of the enemy's walls, as the Greeks so famously did not. Otherwise, they would be called Greeks. And you would be in a great deal of trouble, my friend!
The greatest irony - the analogue hinges on the fact that thousands of years after their defeat, Trojans are once again famous for being the vessels in which sauce is kept weak.
That or, y'know, the first modern adaptation of the condom was developed in 1921, when a factory worker in Akron, OH, Alfred Trojan, accidentally dunked his erect penis into a vat of vulcanized rubber.