The coolest of them will be hot as fire in hellfire. Do, not imitate the kuffar:
O Muslims! The Prophet sallallaahu 'alayhi wa sallam said: "You will imitate the nations before you very closely to the extent that if they went into a lizard's hole, you would enter it as well” his companions, may Allaah be pleased with them, inquired: “(Do you mean) the Jews and Christians, O Messenger of Allaah?” He sallallaahu 'alayhi wa sallam replied: "Who else?” (Bukhaari & Muslim). The Prophet sallallaahu 'alayhi wa sallam also said: "The Day of Judgment will not come until my Nation closely imitates the nations before them.” It was asked: “Like the Persians and Romans, Messenger of Allaah?” He sallallaahu 'alayhi wa sallam replied: "Who are the nations (I could mean) except those?” (Bukhaari).
"[You disbelievers are] like those before you; they were stronger than you in power and more abundant in wealth and children. They enjoyed their portion [of worldly enjoyment], and you have enjoyed your portion as those before you enjoyed their portion, and you have engaged [in vanities] like that in which they engaged…" (At-Tawbah: 69).
They look cool but they aren't. This is similar to incident of Hazrat Adam (ra) eating that apple in paradise. The devil made the "forbidden tree" into "tree of life (or eternity)" and this tempted Hazrat Adam (ra) (he and his wife were thrown out of paradise for this). This is similar here: the rapper looks cool because devil makes so otherwise such things should be avoided to (avoid the hell). One thing I learnt about the devil is that he is master of deception as he makes bad things look good.
Another Hadith (this is one of Signs of Qiyamah):
Hadhrat Abu Hurairah (radhiyallahu anhu) narrated that Rasulullah (sallallahu alayhi wasallam) said: "During the last of ages (in close proximity to Qiyaamah) a nation from my Ummah will be disfigured (and transformed) into apes and pigs." The Sahaabah said: "O Rasulullah! Will they be Muslim?" Rasulullah (sallallahu alayhi wasallam) said: "Yes. They will be testifying that there is no deity but Allah and that I am His Rasool, and they will be fasting (in the month of Ramadhaan)." The Sahaabah asked: "O Rasulullah! What will be their condition (to warrant such chastisement)?" Rasulullah (sallallahu alayhi wasallam) said: "They will be indulging in musical instruments, singing girls, musical drums, and they will be consuming liquor. They will one night go to sleep after their liquor and amusement. When they arise in the morning, they will have been disfigured (and transformed into apes and pigs)." (Kaf-fur Ruaa')