Unsure if a guy you’re crushing on feels the same way? Try sidling up close to him and taking a sniff. If you get a hunch that he’s into you, chances are, you’re right! Why? Male perspiration contains pheromones—certain chemicals that communicate messages to other people nearby. And when that message is one that says, “I’m attracted to you”, the female brain detects it, reveals a study out of Rice University.