... because that would be, uh, treason.

[kadioguy]

Damion Seng: Am I the only one who feels like Tom drinks a dozen cups of coffee a day with how energetic he is?

Tom Holland: I drink tea, darling. Well, I do drink coffee if I’m in the States, but when I’m at home I drink tea, because that would be, uh, treason.
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What does the blue part mean?

Does Tom Holland mean drinking tea would be treason against the States, so he has to do that at home (secretly)?
---------
(Source)
https://video.gq.com/watch/actually-me-tom-holland-goes-undercover-on-reddit-youtube-and-twitter
(at time 0:37-0:49)

 

[jutfrank]

No, he means that drinking coffee instead of tea in Britain would be treason.

 

[Rover_KE]

I hope you realise it's not literally treason.;-)

 

[Tdol]

He's overplaying his Britishness for an American audience.