An onlooker told Us Weekly that the pair was dressed incognito in T-shirts and caps, and 'having a great time laughing and dancing as they walked from one ride to another'.
They were 'trying to stay under the radar', but 'looked really close and both very happy'.
'We recognised him immediately and asked him for a picture,' added the witness. '[He and Renee] were both very nice! She was definitely more shy.'
Unaware that his friend was A-Lister Renee, they even asked her to take of photo of them with Stamos. 'We actually didn't recognise her until they were leaving, and she handed my phone back to us.'
And it wasn't long until the same thing happened again with another group by the Splash Mountain ride.
'She struggled a little bit trying to get a picture,' the second fan said. 'We didn't even recognise it was Renee until later.'