It's a song about being alone and not having anyone who really knows you along with not feelling comfortable in yourself.
One possible reason for the "we only come out at night" line is drugs. This is supported by the "the days are much to bright" This could be true though Jimmy was the band member most heavily involved in drugs. Another reason for those lines could be refering to not feeling comfortable with people seeing you. Billy has refers to feelings like that in many of his other songs too.
It's not about vampires or goths!
It's a song about being alone and not having anyone who really knows you along with not feelling comfortable in yourself. One possible reason for the "we only come out at night" line is drugs. This is supported by the "the days are much to bright" This could be true though Jimmy was the band member most heavily involved in drugs. Another reason for those lines could be refering to not feeling comfortable with people seeing you. Billy has refers to feelings like that in many of his other songs too.