I’m really enjoying Discourse, especially how easy it is to navigate, but I am a member of Discourse on other forums and it seems each forum owner can customize Discourse switches to their heart’s content.
So what if anything happens when I have vistited 
for 100 days? 
or how have you set it?
Are there membership milestones?
You can see all the badges you can earn and the criteria for doing so here:
https://forum.endeavouros.com/badges
There is a badge for visiting 100 consecutive days but I am not sure there is anything for 100 days total.
Yes turns out you can become a clown if you work hard… 
I am already 
If you visit any Discourse forum over a few months you get automatically promoted to Trust Level 3. 4 is highest and requires manual promotion by the way.
Trust level requirements vary by forum and usually require more than just visiting but in this case the OP has already reached Trust Level 3.
Guess I should have read this. https://meta.discourse.org/t/trust-level-permissions-table-inc-moderator-roles/224824
You will receive “Aficionado” medal, if visited consecutively.
That comes at 100 consecutive days, not 100 days total.
Of course, if @HMS_Endeavour has never missed a day, that could be the same thing. 
Yes, I did forgot to mention that single word of interest. Typing sentences via mobile is slight tougher for me…
If you really have no life outside of Endeavour like me, you get a badge for 365 consecutive days also.
hmm, I just turned it on every day since February when I finally found
It’s so nice to feel appreciated…warm and fuzzy 
You had already received this medal.
Oh I feel like so appreciated.
Receiving the “admired” badge is the greatest accomplishment and validation in life so far.
TBH, I’m quite proud of my Nice Reply count… To think that 10 people liked over 100 of my posts. Crazy…
Of course, the best badge on the forum is this one:
https://forum.endeavouros.com/badges/116/clown
Is objectively better, because it’s the only animated one 
Yeah, yeah, and your mom uses Arch, I get it, I get it…
Nah, I prefer the bright clown gifs
I hear frogs day and night. I live near a swamp. 
You live in @Kresimir’s heaven!