This is talking about being horny: you can feel the need to have sex in your mind.

“All along the Western front” and “All along the Eastern shore” are lines used to visualize “worldwide,” or coast to coast.
So MGMT’s just talking about global sex.

“Plug it in” is another reference to sex, and the so-called love involved is going to “change the world.”

According to MGMT, the world is for making love.

Instead of Meth’s “from the brain,” Pac uses “to the brain,” which means that he’s not using his brain to hurt you, but he’s hurting your brain.

Confusing? Hurting your brain? That’s exactly what Tupac wants.

Pac’s really saying, “Let’s go inside my world.” The astral plane could refer to his “dream world,” or some such thing where Pac’s 100% in control.

Literally, the same line. In Meth’s song, “Bring the Pain”, the opening to his first verse is the same as Pac’s hook, except for Pac’s usage of “to the brain” versus Meth’s “from the brain.”

Like “living in the fast lane,” or, living life on the dangerous side.

Removes wrinkles, makes your face stiff.
It’ll help her suck his dick for an even longer period of time.

Pharrell’s dick is hard and sweet, like a sucker. She can suck it all day long.