I actually listen to Eminem a lot and I haven't heard about this till recently. I tried to rap Rap God for a solid twenty minutes and then when my mom came from work I had a five minute conversation with her without stuttering or blocking at all. It could have just been a coincidence though. Has anyone else tried this before? If it does make you more fluent, I feel like this is something you would have to repeat but Ed said it just went away after he learned all the lyrics to the MMLP.