Depends which line

At Camden town station (on a crowded Saturday afternoon):
'Please let the passengers off the train first...
Please let the passengers off the train first...
Please let the passengers off the train first...
Let the passengers off the train FIRST!...
Oh go on then, stuff yourselves in like sardines, see if I care, I'm going
home.'

I read this years ago and it stuck with me - wish they said it more!

Other ones (as I googled to find the wording) that also made me giggle:

"Please mind the closing doors..." The doors close... The doors reopen. "Passengers are reminded that the big red slidey things on the side of the train are called the doors. Let's try it again. Please stand clear of the doors." The doors close... "Thank you."

"Please allow the doors to close! Try not to confuse this with 'Please hold the doors open'. The two are distinct and separate instructions."

"Please note that the beeping noise coming from the doors means that the doors are about to close. It does not mean throw yourself or your bags into the doors."

On the Piccadilly Line:
"To the gentleman wearing the long grey coat trying to get on the second
carriage, what part of 'stand clear of the doors' don't you understand?"

'We are now travelling through The Angel Islington station, as you can see The Angel Islington is closed. It would have been nice if they had actually told me, so I could tell you, but no, they don't think about things like that'

'We are taking the scenic route to Barking on the District Line. We will be stopping at all stations to Barking with the exception of Cannon Street. This train does not stop there on Saturdays due to ....(PAUSE) ...total lack of interest.'

'May I remind all passengers that there is strictly no smoking allowed on any part of the Underground. However, if you are smoking a joint it is only fair that you pass it round the rest of the carriage' .

'Covent Garden has been closed due overcrowding. Please alight at Leicester Square and wander around aimlessly with your huge rucksacks until you get to your destination. You never know, they might install escalators one day!'

"Ladies and Gentlemen, do you want the good news first or the bad news? The good news is that last Friday was my birthday and I hit the town and had a great time. I felt sadly let down by the fact that none of you sent me a card! I drive you to work and home each day and not even a card. The bad news is that there is a point's failure somewhere between Stratford and East Ham, which means that we probably won't reach our destination. We may have to stop and return. I won't reverse back up the line - simply get out walk up the platform and go back to where we started. In the mean time if you get bored you can simply talk to the man in front or beside you or opposite you. Let me start you off: 'Hi, my name's Gary how do you do?'."