You know, I’ve been defender of English humour between my friends for a long time since I learnt English so much that my knowledge was pretty enough to understand the humour. The root of all evil is in mistranslations, literal translations, etc. of course. They ruin all wordplays, which English humour is very rich with I think.
For example, some friends of mine don’t know English or don’t speak it fluently. When I make a Russian Reversal, for example, citing original “In the US you can always find a party. In Soviet Russia the party can always find you”. When my friends ask me to translate the joke, they think full stupidity of me until I don’t make a comment about the wordplay in the original joke (in Russian there are two different words for ‘a group of people’ and ‘a political movement’).
That’s why I watch all TV-series with original audio-tracks (those are The Big Bang Theory, House M. D., Warehouse 13, etc.). Besides this I get a lot of experience in understanding spoken English. That’s very important for me.