Bring a large pot of salted water to a boil, then carefully add the corn on the cob and boil 5 minutes, or until bright yellow and tender.
Meanwhile, melt the butter and cajun seasoning together (using the microwave takes about 45 seconds).
Carefully remove the corn to a serving platter, then brush with the butter mixture, squeeze some lime juice on top, then sprinkle with parsley if desired.