Well, it's obvious that the song is about someone that had a lovely time with someone called Donnie. What it's interesting, is that Donnie is a man (he was yours in the summer time). But in the chorus, the lyrics states that Donnie is a boy YOUR girlfriends fell for him. So, I believe that the person who fell in love with Donnie is actually a man too.
Well, it's obvious that the song is about someone that had a lovely time with someone called Donnie. What it's interesting, is that Donnie is a man (he was yours in the summer time). But in the chorus, the lyrics states that Donnie is a boy YOUR girlfriends fell for him. So, I believe that the person who fell in love with Donnie is actually a man too.