The Banana milkshake trauma

Steve E grabs a strawberry smoothie from the fridge, while we’re in the queue for breakfast in the canteen.
“Is that banana milkshake?” I say looking at the yellow bottle next to it.
“Well, “says Steve, “It’s milk and sugar, and a few chemicals thrown in.”
“It’s got banana flavouring in it. They must spend ages experimenting before coming up with the right formula of chemicals to make it taste… nothing like banana.”
Steve E looks at the ingredients on the bottle. “Yes,” he says, “Banana flavouring…and colouring as well to make it yellow.”
“I can’t stand banana flavour milkshake.It’s evil man.” says Dan.
“I was traumatised by a banana milkshake once.”
“What? How were you traumatised by a banana milkshake?”
“Back when I was at Uni’, we were in this minibus going on a trip. The guy next to me was drinking a banana milkshake…and then he spewed.”
“He threw up his milkshake?”
“Yeah man. Everywhere.”
“Was it still yellow when it came out?” Steve E asks.
“No, it was just puke, but the smell of it. It filled the minibus.”
“Were you on your way back, or on your way to where you were going in the minibus?”
“We were on our way to London for the day.”
“So you smelt of banana flavoured puke all day, around London?”
“No, the smell just filled the minibus, making us all feel like we were going to be sick. Like a chain reaction…The funniest thing was that he tried to spew into a bottle.”
“He tried to spew it back into the bottle? That’s not going to work.”
“No”, says Steve E “you would have a wide radius projecting from your mouth.”
“No, you would go for a bag or something. You couldn’t do it into a bottle. Well, at least not without a funnel.”
“Well, even then…the velocity at which it would come out would just fill up the funnel and cause a bottle-neck effect.”
“I wonder if that’s why they call it the bottle-neck effect?”“Maybe that’s why.” Says Steve E.