The sin of Zina (adultery):
1. 100 lashes publically for unmarried adulterous- (Quran 24:2)
2. Punishment of stoning to death for married adulterors in Islamic Sharia (Bukhari, Muslim) ......
3. Whoever does it will get full punishment and multiplied ...punishment in Akhirah- (Quran 25:68-69)
4 The person is not a believer at the time he is doing zina (Bukhari)
5. Punishment of previously unheard of diseases in this world- (Ibn M...ajah,106)
6. Punishment of burning in a pit(fire) without clothes in Barzakh- (Bukhari)
7. Punishment of being swollen and smelling like the worst gutters in Barzakh- (Saheeh at Targheeb991)
Its not "hot" or "fun"-its one of the biggest sins forbidden by Allah.