No illusion stuff, but...
...try to describe the words below by their colour(!).
Note it's possibly best to pick your native language for the desired "effect". One part of the brain will try to analyze the colours, another will try to read the words... don't get confused!
blue blauw blau
green groen grün
orange oranje orange
yellow geel gelb
red rood rot
edit:
hmm, no big deal. Was way better presented on a site where I stole the idea from, but it was in German language only (not knowing German too well will let you describe the words easily by their colour, I guess.)