Bulge Misinterpretation
When someone looks at a guy in a swimsuit, or in tight boxers, and misinterprets the size of the penis in it. Usually, bulge misinterpretation (or BMI) is only used when the estimate was in the favour of the estimand, i.e. several sizes too large.
"I met him in the swimming pool, and I really thought he was packing, but turns out I made quite the bulge misinterpretation! I was thinking salami, but it was more like frankenweenie."
"That's such a bummer! He looks sweet though..."
"That's such a bummer! He looks sweet though..."