Big Pun rose to fame when he met rapper Fat Joe in 1995 and appeared on Fat Joe 's album , Jealous Ones Envy . He first appeared on albums from The Beatnuts , on the track `` Off the Books '' in 1997 , and on Fat Joe 's second album Jealous One 's Envy in 1995 , on the track `` Watch Out '' , prior to signing to Loud Records as a solo artist . Big Pun died of a heart attack at age 28 .