Giant Man wasn’t always giant: he was a scientist guy named Henry Pym who could make himself really big (Giant Man) and really small (Ant Man), and his costume somehow expanded and contracted with him as he grew and shrunk. Giant Man was also in the Avengers with The Hulk. But did Dr. Pym ever share that secret formula for expanding and contracting trousers with Bruce Banner/The Hulk? No! Despite knowing how to solve this embarrassing torn pants syndrome always afflicting The Hulk, Dr. Pym just decided to let Bruce Banner ruin all those pairs of pants for no reason! (Actually, maybe Dr. Pym ran a pants store on the side, Pym’s Pink & Purple Pants Emporium, and he made extra money by selling Bruce Banner all of his replacement pants in bulk. {The slogan could be: “We Sell in Bulk for the Hulk!”} Maybe that’s how he funded all of his research.)
When I consider this, it’s no wonder Giant Man and Ant Man wore masks: if The Hulk recognized him as the guy cashing in on selling him all those pairs of pants when he could have shared the secret of expanding pants with him all along, “Hulk Smash!”
Here’s the Wikipedia page for Henry Pym (The guy who is Giant Man and Ant Man, etc.):
And here’s a comic book cover of Giant Man growing to giant size (notice how his costume is not ripping apart; this is what I’m talking about here. The Hulk could really use help in this department, and they’re on the same team together!):
And here’s a comic book cover showing what would happen if The Hulk found out about the ruse (The Wasp is warning Giant Man that The Hulk is coming after him for never offering to make him a pair of re-sizable slacks. And you can clearly see The Hulk’s pants are torn and frayed and purple.):
