#2: Mi aiuti a cosare quel coso?
The word "cosa", not unlike its English counterpart "thing", can be used in a number of contexts. And while its genericness has led teachers to encourage the use of more specific synonyms in essays, it also means that it is one of the most commonly heard words in spoken Italian; it's no wonder, then, that what is easily the most comprehensive verb form in our language, namely cosare, derives from the word cosa itself.
Cosare is a word you'll only ever hear used in spoken language, being extremely informal and context-related: it's essentially a blanket verb that people use in place of another verb they don't know or remember at the moment.
Provo a cosare la spina, vediamo cosa succede! -- I'll try to [cosare] the plug, let's see what happens!
Let's examine this example (source: Wiktionary): let's say that your TV set, for some reason, doesn't seem to be working. You decide to unplug it and then plug it again, to see if that might help; but as you're informing your friend that you're about to do just that, you suddenly can't remember the word for "unplug". On the spur of the moment, it's not uncommon for people to use "cosare" instead, sometimes only to replace it with the right verb as soon as they remember it. Even though the verb cosare doesn't technically stand for anything in particular, the listener is usually able to decipher its meaning in the sentence thanks to both its linguistic (the word "plug" following the verb) and extralinguistic context (the whole situation).
Something similar happens with nouns: that's when the (equally colloquial) word coso comes into play. Roughly equivalent to expressions such as thingy or thingamabob, it's used to designate something whose name you either can't recall or don't want to say, as well as any object that looks odd or unusual.
Pensavo non potessi oltrepassare il coso elettromagnetico -- I thought you couldn't break the electromagnetic thingy
Russell finds the snipe (from Up)
In the first example, taken from Reverso Context, the speaker can't remember the word "campo", so they use thingy instead.
In the video, when Russell goes to Carl with the snipe, the latter exclaims: "Che cos'è quel coso?!" (1:30 in the video): he's never seen anything like it, and quite evidently finds it weird.
Coso/a can also be used in regard to a person, but that's mainly in a pejorative sense, especially if you're speaking directly to them (as in, I can't even be bothered to remember what their name is)
Senti, coso, non ho tempo da perdere -- Listen, what's-your-name, I have no time to waste
