well, we were coming home tonight and my friends v6 firebird started making a clicking noise, like a belt was loose. it kept getting louder, then the engine clunked and quit. he hasnt changed the oil in a while....any thoughts?

 

Broke a rod? If the oil hasn't been changed in a while, there as a good chance it was a spun bearing (is is a possibility at least). A spun bearing will make a knocking noise from the bottom of the motor. Once the bearing spins, it heats up the connecting rod and can cause the rod to fail (or the bolts to break). If that happens, it will likely jam the crank from turning. This is not to say that is what is wrong, but it is a possibility....mostly based on your mention of a lack of oil changes (how many miles has it been?)