My son has many expressions on his face. This is one of them. Babies dont usually know how to hide their feelings. I guessed he was trying to "expel" something through somewhere while he did this........didnt know whether he succeeded or not because I usually stay away if he does this....except when there's no one around. One time the victim were Uncle Bob and Uncle Farid......they had a hand with Radhi's excrete...everybody does....he even had one on Aunt Shima one time........BIG TIME.....heheh