It's not really anesthesia for colonoscopies or EGDs, but drugs that induce 'conscious sedation': versed, propofol... You are able to respond to commands, but typically don't have a memory of it. As it wears off, you can fool the doctors, too. A doctor thought I was fully conscious and had a conversation with me after a procedure; I have no memory of that conversation. For the EGD, I had a local anesthetic sprayed down my throat right before the sedation kicked in.