Does anyone know anything about how to manage this? My son is nearly 2.5 and at nursery part-time. He's latched onto these two little boys and constantly says their names all the time! (Let's call them Freddy and Billy). If I say let's sing the bus song, he says "no bus song, Freddy song!". He does this with everything!!!!!
Out and about he will say his name is Freddy. Eg at his music class a new teacher asked his name. I said his name is [Flopsy's son] and he said "no, my name is Freddy"!
At nursery the carer spoke to me and said she was a bit concerned as my son is a lovely boy but has started getting rude and sidetracked by these two other boys. She said they are naughty (I don't think she was meant to tell me that) and that my son is perfectly behaved on the rare times they are absent , but when ever they are there he just copies them all the time. He didn't used to do this. They are all between 2-3 years old but I'm a secondary teacher and I feel like it's teenage behaviour!! 

Example, the carers asked the children to sit down in a circle for a story. Freddy and Billy went running round the room shouting bum bum and my son immediately got up and started copying them. Then he wouldn't sit down. He's also started refusing to wash his hands and saying no because Freddy and Billy say no.
When I collected him yesterday the first thing he said to me was "big smelly bum" which is not something he's heard at home so I'm guessing it's another hilarious Freddy Billy thing. He's also started hitting out a bit.
I've seen Freddy and Billy and they are annoying to be honest! (Lighthearted ok!) I know they're only little but they've got a naughty vibe! Freddy always opens the door to mums with a helpful angelic look and then sniggers or blows a raspberry!
My son is really confident so it's not nice seeing him being a follower.
Okay so I know my precious little boy isn't going to be an angel all his life but is there anything I can do to manage this copycat behaviour?
The carer said his behaviour is going downhill and I'm worried the next step is detentions and an ASBO!