This is how Thomas loses his memory goes in Thomas Who?.
[Thomas puffs to the quarry]
Thomas: Hello, Mavis, Bill, Ben, Timothy.
Timothy: Hello, Thomas. We've got lots of trucks to shunt today.
Thomas: I can tell. I'd better get busy.
[an instrumental of Blue Mountain Quarry plays as Thomas, Bill & Ben, Timothy and Mavis shunt the trucks around]
Bill: I'm faster than you, Ben.
Ben: No you aren't!
[they race by with trucks with stone in]
[Ben slams on his brakes but does it too hard and a stone comes flying out of one of his trucks and hits Thomas on the head]
Mavis & Timothy: Thomas!!! [they race over]
Bill & Ben: Sorry! [they race over too]
Mavis: Thomas, are you alright?
Thomas: Whh... who's... [passes out]
Timothy: Oh, dear. We'd better get to the Steamworks. Fast!