Learn Hardcore Turkish: Telefonu sessiz moda alır almaz espri yapmak daha kolay oldu. - As soon as I put the phone on silent mode, making a joke became easier.

It means “as soon as.” It’s formed by repeating the same verb in the aorist (simple present) 3rd person: first affirmative, then negative: V-(A)r V-mez/maz. So alır almaz = “(someone) takes” + “(someone) does not take,” which idiomatically means “no sooner than (someone) takes.” Examples: gelir gelmez (as soon as s/he comes), yazar yazmaz (as soon as s/he writes), başlar başlamaz (as soon as it starts), biter bitmez (as soon as it ends).

Why is it the aorist alır when the main clause is in the past (oldu)?

This construction always uses the aorist in the first part; the tense of the whole event is carried by the main clause. So here the main clause oldu (past) makes the whole sentence past: “As soon as …, it became easier.” For present/future you’d change the main clause: … daha kolay oluyor/olacak.

Does the verb form in alır almaz change with the subject (e.g., “we take”)?

No. The fixed pattern uses 3rd person aorist both times, regardless of the actual subject: alır almaz. You indicate the subject elsewhere in the sentence (with a noun/pronoun or by context): e.g., Biz telefonu … alır almaz ….

What is the -u in telefonu doing?