biff: Definition: Making a mistake and falling down; falling hard. Context: It is used when you or someone else sees a person that has just fallen or is about to fall. It's usually used to make fun of a person who isn't very good. It can also be used amoung friends when describing a time they fell down hard. Social Source: Snowboarders.

bail: ik veronderstel: je opmaken voor een kunstje, maar het toch maar niet doen omdat niet alles goed zit.