Does "rip off' mean "steal" or ...?
I looked rip off in my dictionary. It says "rip off means to steal something". But it has probably a different meaning in the text below from The catcher in the rye;
He was telling us all
about what a swell guy he was, what a hot-shot and all, then all of a sudden
this guy sitting in the row in front of me, Edgar Marsalla, laid this
terrific fart. It was a very crude thing to do, in chapel and all, but it
was also quite amusing. Old Marsalla. He damn near blew the roof off. the headmaster
didn't say anything then, but the next night he made us have compulsory
study hall in the academic building and he came up and made a speech. He
said that the boy that had created the disturbance in chapel wasn't fit to
go to Pencey. We tried to get old Marsalla to rip off another one, right
while old Thurmer was making his speech, but but be wasn't in the right mood

Question

Does "rip off' mean "steal"  or ...?
I looked rip off in my dictionary. It says "rip off means to steal something". But it has probably a different meaning in the text below from The catcher in the rye;
He was telling us all
about what a swell guy he was, what a hot-shot and all, then all of a sudden
this guy sitting in  the  row  in  front of me,  Edgar Marsalla,  laid  this
terrific fart.  It was a  very crude thing to do, in  chapel and all, but it
was also quite amusing. Old Marsalla. He damn near blew the roof off. the headmaster
didn't  say anything then,  but  the next night he  made us have  compulsory
study hall  in the academic building  and  he came up and made  a speech. He
said that the boy that had  created  the disturbance in chapel wasn't fit to
go  to Pencey.  We tried to  get  old Marsalla to rip off another one, right
while  old Thurmer was making  his speech, but but be wasn't in the right  mood

Answer

We have an expression, "let 'er rip!" which means something like to begin, allow or set off. The "rip" analogy comes from the sound of ripping, so the expression is used for noisy actions like starting a motor, firing guns or farting.  The "off" suggests a completed action.

Keep in mind that phrasal verbs sometimes have multiple meanings, and the meaning you need depends on the context.  Expecting a dictionary to always give you an accurate definition for phrasal verbs probably isn't a good idea.

Hope you're enjoying the book! :)

Answer

In your example, 'to rip off another one" means to let go another fart.[ flatulence]