The Trip Mine is a special type of explosive that goes off only when a player interacts with it. There are two ways to arm this explosive, the first is to just press Interact Key (Default F/Enter) while holding it, you will drop the item and see a message to confirm it is armed. Now, whenever this item is picked up, it will explode. The other way to arm this explosive is while it is inside any container , such as a vehicle trunk, a safebox or even a bag, click the item in the list to open it's options menu and click "Arm Trip Mine". Now, whenever that container is opened, it will explode.