My dissertation advisor, generally a man of the left, nonetheless liked to discomfit folks advocating allowing homosexuals to serve openly in the military by asking “would you want to serve on a submarine with one?”
The awkward silence that usually followed adequately made the point of why allowing open homosexuals to serve in the military would be a problem for morale and unit cohesion.
That would bring a whole new meaning to the joke that submarines are "long, hard, and full of seamen." And I'm not talking about a particularly nice meaning.