Sottosopra literally translates to "under-over" but means "upside down" or "topsy-turvy." It's a fun and descriptive word that evokes a sense of playful chaos.
In the song, Tommaso Paradiso sings, "Perché ti piace tutto sottosopra, agitare Coca-Cola" (Because you like everything upside down, shaking Coca-Cola). This line perfectly captures the free-spirited, unpredictable nature of the person he's singing about, suggesting they enjoy life when it's a bit messy and exciting, just like shaking a soda.
Tommaso Paradiso opens by talking himself out of feeling bad about it: "Ma che ti frega? Ma che ti fre' se qualche volta sbagli?" ("But what do you care? What do you care if you get it wrong sometimes?"). His evidence is the weather forecasters and the railway people, who get it wrong every single day and still turn up for work. Two lines later he drops the act and says the real thing: "È un po' che mi manchi col botto" ("I've been missing you like crazy for a while now").
The rest is a man with a phone in his hand. He asks for a photo, the kind that gets him into trouble, then sits there scrolling and "farmi fregare dalle sponsorizzate" ("getting suckered by the sponsored ads"), which is a wonderfully unromantic detail to put in a love song. The chorus is where the title earns itself: she likes everything "sottosopra" ("upside down"), and being around her is like shaking a bottle of Coca-Cola, all pressure and no good way to open it. He is not even surprised by how it goes. "Rifammi fare quei film, che tanto muoiono lì" ("Let me build up those fantasies again, they die there anyway") is someone agreeing to be disappointed before it happens, and then asking for it again.