"Coral Fragging Coral propagation refers to the reproduction of coral and is often accomplished by marine aquarists through a process called fragmentation or, as it is commonly called, “fragging.” Fragging coral is remarkably simple and is an activity in which many reef aquarists become involved."
Lol! I literally just looked up the definition today too! It seems exactly like @Andreas' Reef said, propagating plants. You cut/chip a little off and then put it into a designated “Frag Tank” to heal and grow.