～やがるTo have the nerve to (A), To have the gall to (A), To freaking (A)

やがる is a colloquial usage of the auxiliary verb 上(あ)がる 'to go up' or 'to be complete' that can be attached to the conjunctive form of verbs and will often be translated as 'to have the nerve to (A)', or 'to have the gall to do (A)'. It is primarily used by men in response to actions performed by others that bring about feelings of scorn or disdain.

• あの黒(くろ)の車(くるま)はしょっちゅう俺(おれ)の家(いえ)の前(まえ)に駐車(ちゅうしゃ)しやがるから迷惑(めいわく)してる。

  That black car has the nerve to park in front of my house all the time and it's a nuisance.
• 何(なに)を勝手(かって)なことをしやがる！頼(たの)んでもないことを勝手(かって)にやるな。

  What the heck obnoxious things are you doing! Don't freely do stuff that I didn't even ask you to do.

Alternatively, やがる may also be attached to the て-form of verbs, which is simply an abbreviation of ている + あがる as an auxiliary verb once again. The meaning however will be the same.

• おいおい、また集金(しゅうきん)きてやがるじゃねーかよ。

  Oi oi, as if you're telling me they'd have the nerve to come here collecting money again.
• あんなに注意(ちゅうい)したのに、また犬(いぬ)にちょっかいを出(だ)してやがる。

  Despite warning him that many times, he still has the nerve to bother the dog again.