Melig·State that a person is in when he/she thinks everything is hilarious and as a result will be laughing/giggling constantly, usually for up to an half an hour to an hour. Source
Conculega·An employee of the competitor (Combination of the words concurrent (competitor) and collega (Colleague)). Source
IJsberen·Literally meaning to polar bear walking in circles nervously or out of boredom. Derived from The behavior of polar bears in zoos. Source
Uitwaaien·Literally to blow out; going to the shore to enjoy the blast of the wind and clear one's mind. Source
Natafelen·Literally, after table-ing. To linger after finishing dinner, continuing conversation, having drinks, and enjoying the atmosphere & company. Source
De Engelse ziekte (the English disease)·Applying English grammar and spelling rules to the Dutch language. Source