Complex sentence: The following year she was cast as a totally different character, Mrs. McGillicuddy, Lucy's bird-brained mother, who annoyed Lucy's husband Ricky immeasurably by mistakenly calling him "Mickey" or mistaking him for his fellow bandleader Xavier Cugat.
Split into simpler sentences: The following year she was cast as a totally different character, Mrs. McGillicuddy, Lucy's bird-brained mother. Mrs McGillicuddy would frequently annoy Ricky immeasurably by mistakenly calling him "Mickey" or mistaking him for his fellow bandleader Xavier Cugat.