Sexual forecasting
When a person, in a totally non-sexual context, inadvertently makes a sound or says a word/phrase that is obviously (without a doubt) vocalized in the same way that the person would during sex. This provides a startling, disconcerting glimpse into their private life.
"UGGGGHHHH YESS!!!" moaned Fernanda after seeing her final physics grade. "Whoops ... sorry for that sexual forecasting just then."