Looks like Twitter already took off for the weekend! Right now DownDetector.com is showing that the social network is having issues and thousands of users have reported having trouble, particularly with logging in via the website rather than any of the apps.
When I tried logging in here in the studio, I saw the following:
The good news is that this is literally the definition of a first world problem and we'll all survive without using hashtags for awhile. Twitter should be back up and running at some point today but since I'm awful at grasping the technological intricacies from restoring such a popular website, I could see it taking til tomorrow.