Scruffing is a rare occurrence that alphas perform to other alphas when they lose a fight to become the pack's leader, one of the alphas must challenge the pack leader to a duel to see who wins and becomes pack leader. It's a bite at the back of the neck, where an alpha's dormant omega glands are, which causes the alpha's body to activate its dormant omega genes and change into an omega. The Alpha that does the scruffing often becomes a prime alpha and takes the scruff omega as their mate, the alphas body would change along with the pherememones, it's a week long process of the body shifting to an omegas, fragile build, a womb, ect.

Shigaraki was the leader of The League of Villains, a famous villain group but it was also a pack of alphas. One day, one of the newer members of the League, Guest, challenged Shigaraki for his title, for no specific reason just to see if he could do it. Shigaraki surprisingly accepted rather quickly. Shigaraki being the more dominant alpha won the duel and Guest lay pinned under Shigaraki in the lounge of the base, Twice, Toga and Spinner were watching nervously as they hadn't seen a scruffing before, Compress was comforting Toga and Dabi was smirking, he found this fascinating and wanted to get a good look.