Breakdown of Dat is het walgelijkste wat ik ooit heb geproefd.
ik
I
zijn
to be
hebben
to have
dat
that (het-words)
Questions & Answers about Dat is het walgelijkste wat ik ooit heb geproefd.
Why do we use wat here instead of dat?
Because of the superlative! Even though het walgelijkste acts as a neuter noun (which usually takes dat as a relative pronoun), Dutch has a special rule: always use wat after a neuter superlative.
Where is the word for "thing" in the Dutch sentence?
There isn't one! In Dutch, you can turn a superlative adjective into a noun just by adding an -e to the end and putting het in front of it. So het walgelijkste translates directly to "the most disgusting thing".
Why are the verbs heb geproefd at the very end of the sentence?
The word wat introduces a subordinate clause (a dependent part of the sentence). In Dutch subordinate clauses, all verbs get pushed to the very end. By the way, it is also completely fine to swap them and say geproefd heb!
Why is it walgelijkste and not just walgelijkst?
When you use a superlative as a noun with het, you must add an -e to the end. If it were just an adjective at the end of a sentence (like "that is the most disgusting"), it would stay walgelijkst.