For the last few years I’ve fallen in love with button down collars
But after a few washes that first button starts to fall down and the nerd look starts to go casual with a large amount of undershirt showing
How can I keep my collar up, nerdiness in tact, and minimal undershirt showing?

undershirt not showing is a fit issue
also invest is some collar stays for when you hang up your shirts to keep the collar in shape
sometimes they come with the shirt but keep em in the future and put them in when you are not wearing them

If the collar stays stiff and up
But once you button down a collar it starts to fold out.

The neck measurement is crucial for a good fit. Make sure it's not too big. Also, ties, or is it too hot in TX for that?

I have no ass at all, which presents several problems in terms of clothes fitting properly. Specifically pants since no matter how well-fitting the jeans are, they still look loose on my thighs and upper legs cause of all the extra material that my non-existent ass is supposed to be using.

But more pertinent to the subject at hand - also ostensibly due to my lack of an ass, I for years had an issue where my dress shirts would pull out a little bit from my pants in the back, so there's be all this fucking extra material flailing about on my back. It looked positively terrible. I tried all different sizes of shirts and it was no matter, if it was "regular fit" then the extra flailing material was there and drove me *nuts*. Then a few years back I finally did my diligence and discovered fitted/slim shirts and it changed my whole entire life lol. I see myself in more recent pictures and breathe sighs of relief every time haha.

In a given year I can be up to 210 and down to 175.
One summer my weight got as low as 145 and then as high as 185
I’m trying to work on consistent plans for exercise and sustainability but it’s been at least a decade since I’ve Ben able to have a work life and life that allows that
All to say, I can’t buy fitted shirts because ...

That's crazy.

I stopped wearing them years ago, looks better and is more comfortable having just one shirt on instead of two. Plus the issue you raise re: the shirt showing too much if the collar isn't 100% upright.

But I understand some folks don't feel comfortable w/out an undershirt and/or sweat too much to go buttondown-to-skin so if it's not possible my advice is professional cleaning. Find a local cleaner who's reasonably priced and have them do light starch on your shirts; the collar will stay straight up for several wears each time.

Cause obviously everyone's style is different, and different preferences work for different folks and all that. Probably didn't need to specify that but just want to be sure that you didn't think I was criticizing your preferred style or anything hah.

https://images-na.ssl-images-amazon.com/images/I/4169s4dV4rL._SX466_.jpg

But he has way too much undershirt showing
I also button my collar down
I don’t like the flaps.
Think suit wear but without a tie

I've always had a problem with unbottoning the 2nd button (the one after the neck button) because I feel it shows *too* much chest w/most shirts. I always found that there's no happy medium and it's frustrating. Buttoning that 2nd button makes me look like a stiff, unbuttoning makes me look like I'm trying too hard to be cool haha.

Was shopping at a local men's shop recently and they had a shirt with a small, hidden button between the 2nd and 3rd button. They had a name for this button which is escaping me right now but what a fucking brilliant idea. It solves the extra problem I've always had.

Shirt was $120 so I'll never buy it lol but I hope this is an idea that takes off (if it hasn't already ... that was the first I've seen of it).

Feels like I look like a dude out of a cheesy 80's movie set in Miami if I unbutton the 2nd or 3rd.

Fuck I wish I could remember what they called it. Very clever and apt name.

https://www.amazon.com/s?k=scotch+wardrobe+tape+strips&crid=23ADE8NLHWYSV&sprefix=scotch+war%2Caps%2C243&ref=nb_sb_ss_i_1_10

They default to being way longer and are marketed for women's clothes. But perfect for the problem you mentioned. Cut a small piece and put it between the 2nd and 3rd button and you're good to go.

Depending on the dress shirt I've also used 2 small pieces for the collar to turn any shirt into a hidden button down collar.

Again, marketed towards women, but have been a total game-changer for my work attire.

Thanks !

https://www.amazon.com/gp/product/B078YHXPZ3/ref=ppx_yo_dt_b_asin_title_o01_s00?ie=UTF8&psc=1