This is a song about Pete's jealousy of his ex-lover at the time and essentially this is him conveying his feelings again like he had done Previously on Take This To Your Grave on the track "Tell Mick He Just Made My list of things to do today" Below, i'll provide my take on the lyrics.

Drink down your Gin and Kerosene,
And come spit off bridges with me,
Just to keep us warm.
Light a match to leave me be.
Light a match to leave me.

To use gin and Kerosene on something like a bridge will light it on fire. Pete isn't talking about his ex lover literally burning bridges, but he is using some clever wording to tell her to burn social bridges, such as contact with him. The "Light a match..." section is just as stated before: Pete is saying to his Ex to leave him alone.

I'll keep my jealousy close,
'Cause it's all mine.
And if you say this makes you happy,
Then I'm not the only one lying.

This section is probably one of the less clever of the entire song, but it doesn't take away from the song for being so straight forward. Pete is admitting that he is jealous for how things happened in the situation, and he wants it to just be his. But, the 2nd half is a reference to either the end or very close to the end of the relationship in which they could just be saying things to make each other happy when they knew they were on rocky ground after the cheating incident had been exposed, creating friction.

[Chorus: x2]
Keep quiet,
Nothing comes as easy as you.
Can I lay in your bed all day?
I'll be your best kept secret
And your biggest mistake.
The hand behind this pen relives a failure every day.

First half of the Chorus is escentially Pete saying "stop talking i don't want to hear what you have to say" but at the same time he's saying he wants a break mentally and physically, or just wanting things to go away and have everything go back to how they were in the beginning of the relationship: hence "Can i lay in your bed all day?" Pete continues in the 2nd half of the Chorus by saying even if his ex doesn't mention him in any conversation following their relationship, he's gonna be a secret from all of the guys she dates, but He's also going to be her biggest mistake by cheating on him. The "hand behind this pen..." line is Pete feeling like a failure for her cheating on him, like she wasn't satisfied in the relationship

And I'll keep my jealousy close,
'Cause it's all mine.
And if you say this makes you happy,
Then I'm not the only one lying.

This verse has already been discussed, so no need in continuing the discussion here as it is just for reiteration in the song.

Drink down your Gin and Kerosene,
And come spit off bridges with me,
Just to keep us warm.
Light a match to leave me be.
Light a match to leave me.

As for this part too, it is good for the song to have repetitious verses, but when explaining the lyrics it is not necessary to re-explain what you have already.

[Chorus x2]

So wear me like a locket around your throat.
I'll weigh you down.
I'll watch choke.
You look so good in blue.
You look so good in blue.
[x3]

This part is a bit tricky to explain. Metaphorically speaking, Pete is saying that he is the nicest, most pretty locket people have ever seen and she is getting complements for wearing this locket or whatever(just as an example), but the locket has a secret inside that she cheated on him kind of like in the Scarlet Letter, except she's not literally seen with an A on her clothing. But the secret is going to weigh her down and make her feel uncomfortable because of what she did.(i'll weigh you down, i'll watch you choke) Pete isn't literally going to weigh her down and watch her choke but the pressure of the situation will most likely do that for him.

[Chorus: x3]
[comes back in during chorus 2nd time:]
(So wear me like a locket around your throat.
I'll weigh you down.
I'll watch you choke.
You look so good in blue.

A small detail that is probably not noticed as much in the CD version of this song but in live performances is when backing vocals are provided by Trohman who sings the "keep quiet...." verse while Patrick sings the "So wear me like a locket..." section. Not sure if it is a stylistic thing, but I think there is a hidden meaning for both sections being sung together. Both parts are sung together to add emphesis for the situation, meaning Pete's feelings in the "keep quiet" section and then his thoughts in the "SO wear me like a locket..." section.

This is just my take on things, everyone has their own views. Enjoy :)