You're mad, you know that, right?

We were sitting outside, I began to think of the man that's been living in my head.
'Six inches', I said to myself, out loud.
'What?' My friend asked, pausing.
'He will only sleep if he's six inches off the floor.'
'Who?'
'Well, his name is Peter, but because the girl he loved as a child was French, he prefers Pierre.'
'You know him?'
'Of course I do, he's been living in my head all day.'
'So he isn't real?'
'Well technically not flesh and bone, but real in my head.'
'Okay... So six inches including the mattress?'
'Yes.'
'Yes including the mattress?'
'Why not?'
'Well, A mattress is almost six inches thick. So is the gap six inches and then the mattress starts?'
'Hold on, I'll ask him.'
'Huh?'
'He says the gap has to be six inches.'
'Who says?'
'Pierre.'
'Peter?'
'Yes, but shh, it's Pierre now.'
'Oh.'