Why are kids so fascinated with the Toilet???

so everytime i go to find dj, he is in the bathroom standing up against the toilet looking in.... lol i have to get pictures of him like that. the other morning when i was getting ready he was so excited to see me flush the toilet (i threw my q-tips in there).. so now he throws toilet paper in there just so i can flush it. he has played in the water but thankfully i had cleaned the toilet that morning! little boys are so funny!