What language do they speak?

There are a number of different languages spoken in Malaysia, the main ones being English, Malay and Chinese. Most people speak English so the only real challenge there will be getting past the oft-incomprehensible gabble of sound they call "Manglish". This is a version of English whose mother drank, smoked and dabbled in powerful narcotics during pregnancy, was then exposed to industrial pollutants as a young child, before suffering a head injury in a boating accident in its early teens. At best the result is that a perfectly reasonable question such as "Does Tesco sell this?" becomes "Tesco got sell?" At worst, a conversation degenerates into a slurry of sound lacking articles or grammar, interspersed with "lah" "dee" "one" and "ma".  

 My girlfriend is Chinese, so I've been learning Mandarin with the Rosetta Stone software. It has a rather unique way of teaching in that it doesn't use translations at all - there's no English text whatsoever. It relies on pictures and logical connections to teach you things, and I feel like it's working great. I'm sure after 6 months of daily practising I'll be able to impress the in-laws!