Learn Icelandic: Þetta er svona óvenjuleg tískubóla.

While slík also means "such", svona is extremely common in everyday spoken Icelandic to mean "this kind of" or "such a". Because svona is invariable, it never changes its ending to match the noun, making it much easier to drop into a sentence!

Does svona change the grammar of the adjective that follows it?

No, svona is completely invariable and doesn't affect the declension of the words after it. It doesn't force the following adjective (óvenjuleg) into the weak declension. Since the sentence is a simple "This is..." statement, both óvenjuleg and tískubóla are in the standard strong nominative form.

Why does the sentence start with the neuter Þetta if tískubóla is a feminine noun?

When you introduce a new noun using the structure "This is...", Icelandic always uses the neuter singular pronoun Þetta, regardless of the gender of the noun that comes later in the sentence. You only use the feminine Þessi if it directly attaches to the noun, like in Þessi tískubóla er óvenjuleg (This fad is unusual).

What is the literal translation of tískubóla?

It is a compound word made from tíska (fashion) and bóla (bubble, or even pimple). So a "fashion bubble" perfectly describes a temporary fad or craze that pops up and goes away!