yellow

(...)
The word _bulldozer_ wandered through his mind for a moment in search of something to connect with.
The bulldozer outside the kitchen window was quite a big one. He stared at it.
»Yellow,« he thought and stomped off back to his bedroom to get dressed.
Passing the bathroom he stopped to drink a large glass of water, and another. He began to suspect he was hung over. Why was he hung over? Had he been drinking the night before? He supposed that he must have been. He caught a glint in the shaving mirror. »Yellow,« he thought and stomped on to the bedroom.

-- Arthur Dent in Douglas Adams' »The Hitchhiker's Guide to the Galaxy«