Tree, Expo, Tree!!!

Everyday in the cab, we would certainly pass through Expo and Tanah Merah. Shawn would say in sequence, "Tree" and he points at the palm trees. Then I'll ask where's Expo, he would reply "Star" for the letter X. I said no, it's EXPO. Then he would point to the signage. Next he would say tree again (for train). It seems to me that he is always hoping that everytime he says tree (train), that would make the MRT train appear.