FYI- I can't currently wear t-shirts since I've been either pregnant or nursing for the last 3 years. T-shirts aren't compatible with pregnant/nursing bodies, so I just decline them or immediately give them away when I receive them. Zip-ups are actually the most compatible, of all the clothing swag, and my partner can attest to how frequently I steal his swaggy zip-ups. :)

Generally I think that if there is going to be swag given away, people should get to opt in to swag or such swag should be wholly biodegradable.