Complex sentence: One time, Peppermint Patty lent Thibault a glove which belonged to Charlie Brown, and Thibault refused to give it back, insisting that he'd "fight him for it".
Split into simpler sentences: One time, Peppermint Patty loans Thibault a glove which belongs to Charlie Brown. Thibault refuses to give it back, insisting that he'd "fight him for it".