Anthony keeps trying these drugs “one more time”, then tries to decide if he is going to quit after. But after he gets high he isn’t going to want to quit. So he has to realize that this method isn’t working and he needs to try something else if he really wants to quit.

Watsky turned down approx. $250,000 to do a T-Mobile commercial in which they got a “fast rapper” to advertise the Sidekick 4G.

He then went on to parody it to show how much of a sellout he would’ve been for taking the deal.

http://www.youtube.com/watch?v=M5n6aZxuBms

This line is very similar to the premise of J’s song Too Deep For The Intro. The principle is that he’s scared to tell people his dream is rapping, for fear that he’s going to be made fun of, shot down, or rejected.
In the context of this song, he asks if it’s worth it to tell the girl his dreams, or if that will just scare her.
He elaborates on this in the following line.

Both parts of this sentence are grammatically incorrect, speaking to Gambino’s cleverness.
He says he ‘runs on sentences’, which is saying he has complete control and domination over his words.

Gambino breaks the mould of the traditional gangster rapper, instead deciding to be a completely different persona.
He is brash, nerdy, funny, mean, and lovable, sometimes all in the span of one track, and that is what makes him so strange/weird/unusual.

Although many people see Gambino is a joke, he sees himself as having a rightful place along other chart-topping rappers such as Kid Cudi, Wale, and Drake. This place is well-deserved, as many see Gambino to be smart, lyrical, hilarious, technical, and overall a great rapper.

Clint Eastwood wasn’t pulling the biggest roles back in his younger years – his breakthrough came in the series Rawhide when he was 30. The implication is that Clint was broke as hell in his 20’s, thus having to wear a trash can to keep his clothes whole.

Kinda like this (even if “trash can” rhymes better than “barrel”):

Similar to Clint, The Slim Shady LP didn’t drop until Em was 27, which is considered pretty old for his breakthrough album. But we all know how things took off from there.

He makes a play on the common rapper boast of being ‘g’ or ‘gangster’.
He says instead of being ‘g’, he is ‘g-rated’, which is the MPAA rating for a children’s movie.
He is calling his opponent weak and childish, and saying his music is easy for even a kid to comprehend.

Jay leaves the form of this ‘pressure’ open-ended so that the listener can relate to the concept. This could be the pressure to succeed, the fear of failure, the pressure to make music, or pressure to do certain things in life from society.

Also note the wordplay of “the pressure” as it sounds like “depression,” which is why he has the lonely face.