Breakdown of Går du under stegen, händer något hemskt.
du
you (singular)
gå
to go, to walk
hända
to happen
något
something / any (ett-word)
Questions & Answers about Går du under stegen, händer något hemskt.
Why does the sentence start with the verb går instead of om du går?
This is an inverted conditional clause. In Swedish, you can drop the word om (if) and start the clause directly with the verb. Går du... means exactly the same as Om du går... (If you walk...).
Why is the second part händer något instead of något händer?
This is the V2 (verb-second) rule in action! The entire first clause (Går du under stegen) acts as the first block of information. Because the verb must come second, händer has to be the very next word after the comma.
Why does hemsk (awful) have a -t at the end here?
The adjective hemskt is describing något (something). Pronouns like något (something), allt (everything), and inget (nothing) act as neuter words, so any adjectives describing them must take the neuter -t ending.
Wait, doesn't stegen mean "the steps"?
It can, but not here! This is a tricky pair of twins. Stegen is the definite singular form of en stege (a ladder). It happens to look exactly the same as the definite plural of ett steg (a step). Context tells us this is about walking under a ladder.