My personal favorite is a very strange version of the Sicilian Defense; Old Sicilian Variation. The exact pattern is shown on the board.
Okay, well not exactly because the 250-Elo bot wanted to be very aggressive for no reason, but the moveset for white was going to be; e4, Nf3, Bc4, d3, Nc3, Be3, and finally O-O (kingside castling). I think.
⚡️The reason I usually try to go for this opening is because, even if I get interrupted during development like in the game shown, it’s still a very flexible opening that controls many squares, and can be pretty hard for your opponent to play against, usually because it’s hard to hide their newly developed pieces from your wide arsenal that sees half the board.
‼️And now, if they try to be aggressive, you can easily counterattack with one of your pawns or other pieces. Then, about by the time you castle if you want, you can start using your own plan to win!
⭐️ That was a short example of an opening. You can introduce one too! Just make a post about it so the chess world knows. 
I should really admit that ANYONE BUT a 400-Elo idiot such as myself should be doing this, but oh well. Anywho, welcome to the forum! Here, you can post your favorite random opening ideas to share with the community! Some may be widely used, while others completely unknown and made yourself! Then, you can show us how to use said opening, and just why you love it so much. I’d love to see the collection of player-made openings grow as much as possible, so post away while I figure out how any of these forum features work. What surprises can you introduce to the chess community?