asshole wouldn't pucker up tighter than a snare drum

[giddyman]

Hello, teachers.

Please help me with a line in the screenplay of Shawshank Redemption. I think I know what it would mean in the context, but I want to know how the metaphor works. Please check the underlined below. Thank you.

Andy: Ask the warden for funds.
Brooks: Oh, son, son, son. Six wardens have been through here in my tenure, and I've learned one immutable universal truth; not one of 'em born... whose asshole wouldn't pucker up tighter than a snare drum when you ask for funds.

 

[jutfrank]

Some people may refer to those people who are 'tight' (not generous) with money as 'tight asses'.

Does that help?