It's just my way of saying "I'm an asshole, and I'm sorry. Forgive me," in song. But I really like British slang, so I built the whole song around the term wanker, which means pretty much the same thing as asshole here.
Lyrics
I'm a wanker and I know it
Though I needed you to show it
I will not let this live with me
If you decide you'll forgive me
I'm a jerk and you have told me
So I'm coming to you boldly
Can you put the past behind us
And beg fortune be kind to us
I know my luck is running out
I know I make you scream and shout
I know my luck is running out
I know I make you scream and shout
I'm a loser but you tell me
About the day that you fell for me
Is it supposed to make me feel good
When you talk about my manhood
When it comes to your love I'm blind
I'll try to make it better, be kind
I'm sorry that I had to hurt you
I promise that your suffering is through
I know my luck is running out
I know I make you scream and shout
I'm a wanker and I know it
I'm a wanker and I know it
