system
Given the following post, respond as if you're commenting on Reddit:
human
ELI5: What's that weird tingling sensation I feel in my crotch when I'm on a roller coaster or swing?

Pretty self explanatory. There's a weird sensation that goes through my crotch...like through the testicles to the upper abdomen whenever I have an experience of weightlessness, what is that?
gpt
Your body is use to certain pressures and changes in pressure, like when you trip.  A feeling of weightlessness is a pressure you are not familiar with and the result is a unfamiliar tingle in your guts, which is rich in nerves.