The speaker was Hugh Baker, an emeritus professor at SOAS. He talked a bit about the now-defunct China Coast Pidgin, which was interesting, but unfortunately revealed also that he didn't know an awful lot about pidgins and creoles. (He compared the completely analytic nature of pidgin verbs and its use of 'piecee' with numerals — e.g. 'two piecee car' = 'two cars' — directly with Chinese languages, without seeming to be aware that single-form verbs and qualifiers such as Tok Pisin's 'wanpela, tupela' are common pidgin traits.
There's already some information about it here, and there's a pdf here that contains part of a similar talk — scroll down to page 7.
The most interesting bit of the talk was when he was describing puns made by Cantonese speakers that depend on a middle term that has been missed out (like rhyming slang 'aris' = 'Aristotle' = 'bottle' = 'bottle and glass' = 'arse', or 'Hovis' = 'brown bread' = 'dead'). Some of these only work if you have some knowledge of another language besides Cantonese. The clearest example of this was when he said he hoped we wouldn't get "Foreigners' yut-beng", or "bored stiff". The pun apparently works because, if you say 番鬼佬月餅 (faan-gwai-lou yut-beng) it refers to what English-speaking foreigners say instead of yut-beng: they call it ‘mooncake’ - and ‘mooncake’ sounds like the Cantonese mun-gik 悶極 which means ‘extremely bored’.
A lot of the other examples ("African bonze", meaning "black Buddhist priest", which sounds like a word for 'horrible', apparently) didn't really stick with me, because I don't know any Chinese languages. But we did wonder if there weren't more examples to be found of this kind of thing: specifically, with English, I wondered about Welsh or Gaelic speakers, who would presumably be fluent enough in English to pun in either language. So: any good examples of multilingual puns out there?