Complex sentence: When Kathy thinks Jenny is hearing things, she laughingly opens the closet, but discovers inside are two people dressed strangely, apparently out of sync draped in a great light, who return her pencil mug.
Split into simpler sentences: When Kathy thinks Jenny is hearing things, she laughingly opens the closet. Inside are two people dressed strangely, apparently out of sync draped in a great light, who return her pencil mug.