A green bomb that will follow your weak armored dudes around and blow them the fuck up. They actually just want hugs; however, your silly bros keep shooting them up, hence the explosion. Some people think these little cute bombs are overpowered, but then again, some people just mass marines every match-up.
Hey look at th-
*Green cum explosion*
Hey, those Banelings are overpowered. Let me complain while I pump out my perfectly fair Thor/Siege tank combo.