Tensed verb preceding infinitive verb in modal relative clauses?

Question

In the recent Ohrwurm "Geiles Leben" by Glasperlenspiel, the following verses can be heard (at 0:24):

Was du heute kannst besorgen

Das schiebst du ganz entspannt auf morgen

(cf. songtexte.com)

I have never come across Was SUBJECT AUXILIARY-VERB ... MAIN-VERB either in spoken or written form before; How can this sentence be analyzed syntactically? — For myself (albeit not a native speaker), a different permutation of the words above is completely acceptable and unremarkable:

Was du heute besorgen kannst — Das schiebst du ganz entspannt auf morgen.

Despite the original verse being "wrong" to me, I can find the usage of SVO word order in dependent clauses acceptable, but only with the word weil when responding to a(n either explicit or implicit) question (cf. Weil das ist ein Nebensatz). Is this the same phenomenon being generalized, or is there another explanation?

Answer 1

The reason they put the sentence in this order is a pun with a very common German proverb of unknown origin:

Was du heute kannst besorgen, das verschiebe nicht auf morgen.

The word order was adapted to meet rhyme metrics, which is often found in poems.

Answer 2

As Takkat said, the word order appears to be taken from the common proverb. However, the reason why the proverb has an unusual word order is probably its age. The order of verbs in end position has only become fixed quite recently, maybe in the 18th century. To this day, the order auxiliary–main verb (… kannst besorgen) is common in Switzerland, and vestiges can be found in other places, see Verbstellungen « atlas-alltagssprache.

Of course, the order was du heute kannst besorgen is not SOV, but rather OSV, exactly like the order was du heute besorgen kannst. Both have the verbal complex in the final position, as is normal with normal German relative clauses (and the object is fronted because it is used in the relative particle which must come first). The object is was, the subject is du and the verbal complex is kannst besorgen, with besorgen being the main verb.