DeadliftsThe king of strength movements, the deadlift (done properly) will add muscle mass throughout the whole body. Whilst many of the typical gym rats thinks the deadlift is a lower body lift, find me a guy deadlifting over 500lbs who doesn't have enormous guns.
The deadlift involves a large activation of the muscles on your arms - building both an impressive grip and a monster set of biceps. The whole body nature of the exercise means that you get a big testosterone boost post workout. This helps pack on even more muscle mass.
Weighted ChinsChin ups are probably the original strength training movement for humans. Aside from picking things up and pushing them overhead, there's no greater challenge as a "show of strength" than a good, old-fashioned chin up. But what's this about the weighted component?
Put on a weightlifting belt and tie on some additional weight. Then perform a chin up. If you've got to the stage where 10 unweighted chin ups are easy, add in some extra weight and watch those guns explode!
Tire FlipsA classic strongman event, the tire flip is another full body exercise that doesn't get enough love in the mainstream fitness media. Like a deadlift, the tire requires strength in grip and bicep, but maintains the tension against your biceps across the entire lift. The huge weights being moved on this event (well over 800lb tires in many contests) means there's a huge growth stimulus placed on these muscles.
Pro tip - warm your biceps up with regular curls before these events. Many competitive strongmen get gruesome bicep tear injuries whilst competing - showing just how much stress your guns take when completing this lift.
Barbell RowsGet rowing. Bent over barbell rows are another multi-joint, compound exercise that builds muscle across the biceps, forearms and back. Perform these with your palms facing forward to get even greater effect.
Barbell CurlsOK, I had to chuck this one in there. The classic bicep exercise allows the most weight to be used with a very simple form to master. These should be used as an accessory lift (yes, your primary goal in the gym should not be one of your smallest muscle groups). But they can be included once your big heavy work is done for the day.