Lyric discussion by anggg417 

Cover art for 18 lyrics by 5 Seconds of Summer

18 is about the struggle of being young but still wanting to do things and live a little. The lead vocalist is younger than his band mates, so during the writing of this song he could not drink and party as the other could since he was underage.

My Interpretation

@anggg417 in Australia the legal age for drinking is also 18.