Use Giant Sets To Gain Giant Size
Giant sets are typically sets of 3 different exercises performed in rapid succession. For example, a giant set for the delts could be the military press, the side lateral, and the bent-over dumbbell laterals. Each of these exercises works out a different head of the deltoid, which is a three-headed muscle.
You could also do 4 or 5 exercises in this fashion. For example, you could do a set of flyes, then benches, then pull-overs, inclines, and dips. This regimen would seriously impact your ability to hug your loved ones for a while!
Now that you know what giant sets are, you've got to ask yourself why and when would I ever use them?
High Intensity Training provides the why. You can really blast your muscles if you make them do giant sets. You'll be placing an extraordinary load on them and they'll be forced to adapt (remember Progressive Resistance Exercise (PRE)).
You'll want to incorporate giant sets into your work-out routines whenever you want to stimulate new growth in a stubborn muscle group, but you'll only want to use them sparingly, as over doing them might (will) lead to over-training.