If you've ever done an experiment like this (there are smaller scale versions), they are very weird. I can't imagine a full body experience.
Example:
The one I have done involves sitting behind someone, eyes closed, and having your nose stroked (by a third party) while you stroke someone else's nose in front of you. After a few seconds, your brain "clicks" and you feel like you have an incredibly long nose. This is because of the feedback loop where your brain feels something on your nose and your finger simultaneously, and your mental body image just changes instantly.
There are two ways to write error-free programs; only the third one works.