Can someone, please, explain to me what that is about? Is it some sort of event I should be checking? I'm missing out achievements if I don't act now fast?

Kissing is part of the Survival/Pandemic event in February. Dancing is part of the Masquerade event in March. You aren't able to kiss at any other time outside of the Survival event, and same for dancing with Masq.

Also there's Trick or Treating during Morostide in October, and same rules apply.

If you're talking about the billboard ads on top of the forums talking about kissing, users submitted those back in February for Survival and...they're still lingering, even though the kiss links aren't functional right now.

Edit: Yes, there are achievements. Check the Achievements page, then look at the different events. Look for the event forums which pop up during the event, there are usually chat threads, etc where you can go and get some achievements knocked out of the way. Plus, event currency and event stores with cool items are going on as well.

Edit to the Edit: The news page has a "Check it Out" section in the sidebar that has links to whatever current event forum, event store, etc is happening at the moment. I find it very handy for quick links to event things.

Oh. There are some kiss links, but it seems like they are no longer functional.

But what about dancing? Should I be dancing with people right now? It says I need a mask.

Kissing is from the Survival event last month, which has ended. But you might be seeing the buttons around on top of the forums still. Some users used billboards (user created ads) to put their buttons up there, and they're still around because they have impressions left.

You might also see Kiss buttons on forum signatures, from people who haven't changed them yet.

The Dance buttons are for Masquerade, which is happening at the moment. Check out the Masq. event forum here.

Both buttons are used to earn currency for their respective event. Candy hearts for kissing during Survival (but the kiss buttons don't work while the event is not on, so ignore those). Masq. has Steamworks and Lounge Trinkets, earned by dancing with other users. The dance button will stop working when the event ends.

Click on your sP on the side bar to go to the currency page, and you can see these and other currencies there, as well as go to the shops that accept them. Subetapedia has information on the holidays.

I'm actually a bit surprised that there isn't a FAQ in the Masq event forum. It can be a bit confusing. Here's the news post about the current event:

A bit about Masquerade

You may not have seen my edits. I will again recommend the "Check it Out" section in the sidebar of the news page. It's very handy.

Also, Survival and Masq happen every year. If you don't manage all or even some of the achievements, don't sweat it too much!

That should be all of the info I need. I'm going to check it all now and try to get some dances in, as fast as possible. Thanks!

right now the subetapoints price of both Lounge Trinkets and Steamworks Trinkets on the open market is at the lowest it's been for around five years. Do your Sarah Quests at least, or all of the quests you can stand otherwise. This way you can earn yourself some sP to buy any extra Trinkets you can't score by dancing. The price will creep up again over the next year, so around now is the time to buy them if you find items from these shops interesting.