What's my stepdad's problem?

So today I was downloading something and left it to load overnight and i woke up and it was cancelled. i asked my stepdad and he says my mom cancelled it so i asked her but she says she didn't do anything and she calls him over to ask him why he lied. they didn't get in a huge argument or anything but slight confrontation. THEN after she leaves he starts complaining to me on how i tattle on him when i was simpling asking a question to my mom. then he lectures me on respecting my elders which doesn't make any sense in the situation and i just ignored him. then he gets pissy and was like "YOURE JUST GONNA END UP AS TRAILER TRASH ANYWAY" and he never insulted me like that befre. and i srsly don't get his problem. why is he so freaking pissed over a damn download of which he lied about in the first place.