The Syringe can be used for a variety of purposes, some helpful and some harmful.
Operation of the Syringe Edit
First you must hold the Syringe in one of your hands, if it is already filled, skip this next part.
Click on the Syringe - the text should change from "inject" to "draw" - then pick up your desired solution with your other hand and switch to the Syringe holding hand. Click on the solution, and your Syringe will now have five units of solution in it - it may hold up to fifteen. Change the Syringe back from "draw" to "inject" and put the solution away and you are ready for some fun!
Finally, simply click on your desired target (who must be adjacent to you, see range) and you will attempt to inject him with the drugs.