Complex sentence: Rodrick is Greg's aggressive, antagonistic, slacker older brother; a drummer in a garage band humorously labelled "Löded Diper" (loaded diaper), noted for their substandard heavy metal concerts and limited musical abilities.
Split into simpler sentences: Rodrick is Greg's aggressive, antagonistic, slacker older brother. He is the drummer in a garage band humorously labelled "Löded Diper" (loaded diaper), noted for their substandard heavy metal concerts and limited musical abilities.