What does Das mean?

Before the gala he still had to find a decent das.

Dutch student slang. This is a Dutch word. You will hear it a lot at Dutch universities, student associations and in student houses.

Within an association or dispuut the das is often part of the fixed dress code for borrels and official events. Sometimes even with its own colours. Lose it and you will hear about it. Also read about jasje dasje and fit check.