a spider's web traps himself
It literally means a spider's web traps himself. It's a saying used when someone who tries to put other people into trouble ends up being caught in his own trap. And therefore you should not try to put people into trouble lest you get caught up in your own evil trap(machinations or manipulations). The word "anancy" used there means a spider with etymology traced to the Fante(Akan) language spoken in Ghana formerly The Gold Coast.
Patois: a him dash weh the banana skin round the corner and did look mi fi step pan it and fall and now see wah a gwaan. A him deh a grung now. Member, anancy rope tie anancy
English: It's him who threw the banana peel around the corner and wanted me to step on it and trip and now see what's happening. It's him on the ground now (rather). Remember, don't try put people into trouble lest you get caught up in your own trap.