#JavaScript 259 240 238 bytes

Not that good but might as well post an answer.

b=String.prototype,b.a=b.replace,alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4.".a(/1/g,"I'm ").a(/2/g,"Slim ").a(/3/g,"Shady").a(/4/g,"lease stand up").a(/5/g,"real ").a(/6/g,"the ").a(/7/g,".\n"))

More readable version :

b=String.prototype
b.a=b.replace
alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4."
    .a(/1/g,"I'm ")
    .a(/2/g,"Slim ")
    .a(/3/g,"Shady")
    .a(/4/g,"lease stand up")
    .a(/5/g,"real ")
    .a(/6/g,"the ")
    .a(/7/g,".\n")
    )

JavaScript 259 240 238 bytes

Not that good but might as well post an answer.

b=String.prototype,b.a=b.replace,alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4.".a(/1/g,"I'm ").a(/2/g,"Slim ").a(/3/g,"Shady").a(/4/g,"lease stand up").a(/5/g,"real ").a(/6/g,"the ").a(/7/g,".\n"))

More readable version :

b=String.prototype
b.a=b.replace
alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4."
    .a(/1/g,"I'm ")
    .a(/2/g,"Slim ")
    .a(/3/g,"Shady")
    .a(/4/g,"lease stand up")
    .a(/5/g,"real ")
    .a(/6/g,"the ")
    .a(/7/g,".\n")
    )

#JavaScript 259 240 bytes

Not that good but might as well post an answer.

b=String.prototype
b.a=b.replace
alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4.".a(/1/g,"I'm ").a(/2/g,"Slim ").a(/3/g,"Shady").a(/4/g,"lease stand up").a(/5/g,"real ").a(/6/g,"the ").a(/7/g,".\n"))

#JavaScript 259 240 238 bytes

Not that good but might as well post an answer.

b=String.prototype,b.a=b.replace,alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4.".a(/1/g,"I'm ").a(/2/g,"Slim ").a(/3/g,"Shady").a(/4/g,"lease stand up").a(/5/g,"real ").a(/6/g,"the ").a(/7/g,".\n"))

More readable version :

b=String.prototype
b.a=b.replace
alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4."
    .a(/1/g,"I'm ")
    .a(/2/g,"Slim ")
    .a(/3/g,"Shady")
    .a(/4/g,"lease stand up")
    .a(/5/g,"real ")
    .a(/6/g,"the ")
    .a(/7/g,".\n")
    )

#JavaScript 259 bytes

Not that good but might as well post an answer.

b=String.prototype
b.a=b.replace
alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 please 4?\n84. 84.".a(/1/g,"I'm ").a(/2/g,"Slim ").a(/3/g,"Shady").a(/4/g,"stand up").a(/5/g,"real ").a(/6/g,"the ").a(/7/g,".\n").a(/8/g,"Please "));

#JavaScript 259 240 bytes

Not that good but might as well post an answer.

b=String.prototype
b.a=b.replace
alert("123. Yes, 16537All you other 23s are just imitating7So, won't 6523 p4?\nP4. P4.".a(/1/g,"I'm ").a(/2/g,"Slim ").a(/3/g,"Shady").a(/4/g,"lease stand up").a(/5/g,"real ").a(/6/g,"the ").a(/7/g,".\n"))