Seriously, don't even bother with thinking about all of the mental excuses about how you're going to weasel yourself out of it and explain it away if someone questions you.
Here's my experience:
Nobody gives a s***.
The worst that will happen is maybe some random person that you've never met before and will likely never see again as long as you live will look at you, maybe they'll wonder why you're in the women's section for a brief second, and then they'll probably just assume that you're shopping for your wife or something, maybe they'll chuckle and wonder if you're in there for yourself jokingly, and then that fleeting thought will pass out of their mind as quickly as it entered it, they'll go back to being wrapped up in their own stupid lives, and will completely forget that they ever even saw you, or that you even exist, within 5 minutes of leaving the store.
Seriously. Nobody cares.
I bought panties for myself several times, at the Walmart that I was working at for crying out loud, and the worst that ever happened was that one of my female cashier friends joked around with me about "you'll look pretty in them," we both laughed like it was a big joke, that was it, she never mentioned it again, and then a month later she transferred stores and I never saw her again.
Again. Nobody cares. Even if they know who you are, and see you deliberately walking into the women's section, and the cashier that checks you out not only knows you, but you work with her every single day, they still don't care.
So here's my advice... go shopping, have a ball, try on whatever you want, quit worrying so damned much about being seen by all of the people around you, quit acting like a nighttime sneak thief trying to infiltrate enemy territory, and just enjoy yourself. Nobody cares.