Nothing. Let him sleep and fart peacefully. The most important sport for toddlers is swimming anyway. For obvious reasons. You don’t want him to drown in a friends pool. It’s also good for preventing colds.We don't have BJJ for 3 year olds around here.
What do you guys recommend for a 3 year old?
Real martial arts should be taught after they become 12. Bone structure, memory etc. I think even BJJ only starts really counting for belts after 16 year old. But I could be wrong.
If you want him to do self defense in school just teach him how to throw an elbow strike. Believe me it’s more than enough and nobody will mess with him. The schools staff might not enjoy it much.
Until they’re 12 years old I only do some light lessons with my kids. Mostly defense.
The front kick is really a good way to defend without hurting the other person much.