1. When referring to connection types, DIN was an architectural specification defined by the Deutsche Institut fuer Normung, a German standardization group. Computer keyboards, computer mice, network routers, video appliances, and Apple serial devices are a few examples of hardware devices that may use a DIN style of connector. Today, the keyboard 5 DIN connector has been replaced by the PS/2 and USB connectors.

5 pin DIN specification

Pin Voltage Assignment
1 +2.0 to +5.5v Keyboard Clock
2 +4.8 to +5.5v Keyboard Data
3 +2.0 to +5.5v Reserved
4 Ground Ground
5 +2.0 to +5.5v +5.0V DC

2. Shorthand for Do It Now, DIN is commonly used in chat rooms and online gaming. Below is an example of how this could be used in chat.

User1: You should really go visit that site.
User2: Don't worry I'll get to it sooner or later.
User1: DIN!!!
User2: Ok, ok!

Also see: Chat terms, Game terms, ISO