Would you lepeat that, prease?

Here's a communication exercise for foreign learners of English. You put two students at either end of a table with a screen between them so that they can hear but not see each other. You give one a lorry made out of lego pieces, and you give the other student just the pieces. The task is for the one with the made-up lorry to instruct the other how to construct a lorry from the pieces he has in front of him. The first task is, of course, to invent terms to describe lego pieces. In setting up this exercise, the teacher simply says to the two victims that the task is to construct a lorry.
Great.
So, I used this communication exercise as a demonstration in a workshop I was doing in Japan. It was a total disaster, like those experiments in the chemistry laboratory where instead of a blinding phosphorescent flash, you get a damp phutt.
What went wrong? Two things, I suspect. First, the Japanese have a problem with the pronunciation of the sounds [l] and [r]. For them, these two sounds are allophones of a single phoneme, giving rise to all those hilarious jokes about the Magic Fruit, Gleek plicks, and so on. Secondly, most Japanese learn American English, so the word lorry - or lolly or rolly or rorry - is in any case unknown to them. For them, the vehicle is a truck.
Phutt.
Fortunately, time is a great healer of egg-stained faces.