My arms and shoulders ache. I was thinking in the shower last night. Very bad idea. I wasn't paying attention and I kept scrubbing my hair... I don't know how long I scrubbed, but I went to push my hair back with both arms today (kinda in the position for hair scrubbing) and suddenly felt the muscles go "HHHHWWWWAAAAAAAAAAAAAAA!!!!!!!!!!"
Scalp is still there though...