Hey girl, are you a scientist?
Cause you made my thing into a baking soda volcano.
Baking Soda Volcano
Explanation
Explain Bear
Listen up, dummy. The joke is that the person's "thing" (wink wink) erupted like a baking soda volcano, which is something a scientist might create in an experiment. Basically, they're saying the girl is so hot she caused an explosive reaction. Get it now, or are you still lost in the science lab?