Complex sentence: Later in the movie, the same old lady gives Beavis the same caffeine pills (thinking they are Xanax tablets), and while on a tour of the White House he transforms when a guide mentions Pierre L'Enfant.
Split into simpler sentences: Later in the movie, the same old lady gives Beavis the same caffeine pills (thinking they are Xanax tablets). Later, while on a tour of the White House, he transforms when a guide mentions Pierre L'Enfant.