Continues the birthday theme…while Voss is down to “cut” (have sex) with the girl, she cannot have his “cake” (or money) for him to do so.
Someone who pays for sex is referred to as a “trick”. Voss turns that phrase into a play on Trix brand cereal, whose slogan is “Trix are for kids”, meaning here that a grown man shouldn’t be paying to try to have sex.
“I ain’t no silly rabbit” is a reference to the Trix mascot:

A reference to 50 Cent’s famous hook from “In Da Club”, followed by a reference to the common term “birthday suit”, meaning naked.
Since she’s partying like it’s her birthday, she might as well “put on” her birthday suit.

Reese is committed to hip-hop, which he compares to being “Facebook official”, a term used for when a relationship becomes the “real deal” since the couple makes their commitment public on Facebook.

When Reese and Voss write together, they do so like a bawwwwse, similar to how a president would conduct their business.

The crazy lyrics that Reese spits are so hot that they’ll burn your brain, or “medulla”, which would in turn mean your “mind ain’t right” anymore, since it’s kinda sorta charred to a crisp.

Voss’s verses are as dangerous as a Ruger firearm. This is a Ruger:

so back the fuck up

Voss is indeed a trained character assassin with impeccable aim, who will make you cry to mommy.

Voss will turn the opposition’s rap career to nothing but a smoking crater if they challenge him, in turn “murking” (terminating) their future in music.

Voss may be young, but he’s got the wise soul of someone twice his age.
That’s not like Benjamin Button is it? I dunno, I never saw it.

Slang term essentially meaning “calm down”