Complex sentence: Allaudin (Bill) Mathieu called out "Harold", which was a joking reference to a line from "A Hard Day's Night" where a reporter asks George Harrison what he calls his haircut and he answers "Arthur".
Split into simpler sentences: Allaudin (Bill) Mathieu called out "Harold". It was a joking reference to a line from "A Hard Days Night", where a reporter asked George Harrison what he called his haircut and he answered "Arthur".