I think the most disrespectful opening is the Transvestite opening where the person moves the pieces around just to swap the places with the King and Queen. A lot of people call this the Magnus Carlsen Gambit, but I don't think he invented it. It's just a fun trolling opening when you want to see how badly you can play, and still come back and win the game (hopefully).
I test these kinds of openings out on lichess, and a good strategy with them is to just launch flank pawns to start an attack. I've won some nice attacking games this way.
That's one way to do it. Magnus pushes his C and F pawns forward, moves the Queen to A4, H4, moves the King to D1, then Queen to E1. I saw him do this once against a grandmaster who knew what Magnus was doing and moved his pawn to B5 to block the Queen. What did Magnus do? He just moved F3, then marched the King to F2, E3, D3, C2, and down to D1. He gave 8 free moves to a GM and even with the other GM being up so many moves, Magnus still came back and won. That's the ultimate disrespect.
I'd think anybody playing Anna Crambling's Cow Opening could consider that a disrespectful opening. She recorded a video showing her new opening to her two GM parents and they were trying to be kind and not tell her just how horrible the opening was.
The Magnus Carlsen Gambit, of course:
Is that an actual gambit?
No. Theory moves always end when a bad move is played.