Four engineers travelling in a public bus once,
1st: (to 2nd and 3rd) Man you guys really think that we'll be get married in near future, just 7 or 8 years to go?
2nd: Let's design a pact, we'll go to honeymoon together, and just for a night we'll exchange our wives
1st: No, I won't let you fuck my wife; instead I'll misguide and fuck your wife
3rd: Don't kid guys; your wives are gonna come to me, after all what an unsatisfied woman could do?
1st and 2nd: Fuck you! You're impotent, you can't do anything
3rd: So what, you losers don't even have potency to have a kid, you expect me to do that?
Both the engineers didn't had enough courage to be humiliated, they begged to change the topic, out of that fourth engineer was wondering out of the dismay that do they really have the courage to do what they said, or it was just for fun.
Meet me, I'm the fourth engineer