The middle of the semester is one of the hardest times of the year, with midterms happening, papers and projects being due, and trying to make summer plans in the middle of everything else.
Pet a dog
Honestly, those frat "pet a puppy" events are probably the best use of five dollars during midterm season.
Go to the gym
Even if you don't anything at the gym, the physical action of walking to the gym and getting out in the fresh air is a perfect break on days when you can't stress over school much longer. And, while you're at the gym, you can do whatever exercises help you the most. For me, weightlifting calms me down, but for plenty of others, running on the treadmill is all it takes to melt away the stress.
Eat junk food
So, they really recommend that you eat healthy food when you're stressed --something about regulating your body, but that isn't what you need when you're really stressed temporarily. To feel better about the exam you just took, just do what you do after a breakup and eat a tub of ice cream.
Go to a bar or club
Or a party (in a post-pandemic world.) These places are busy and fun and get your mind off basically anything if you choose to let them.
Take a spa day
This obviously hard to do on campus, but you can dedicate, like, half a day to pampering yourself. You can take an extra long shower use face masks, and hair masks, and paint your nails, and stay in a fluffy robe all day long.
This is particularly useful if you can walk to the stores because you get the stress-relieving effects of walking, as well as the less healthy stress relief of spending money on things you don't need.