#couple
Defined as:

noun:
couple; plural noun: couples

1.
two individuals of the same sort considered together.
"a couple of girls were playing marbles"

a pair of partners in a dance or game.

MECHANICS

a pair of equal and parallel forces acting in opposite directions, and tending to cause rotation about an axis perpendicular to the plane containing them.

2.
two people who are married, engaged, or otherwise closely associated romantically or sexually.
"in three weeks the couple fell in love and became engaged"

3. INFORMAL

an indefinite small number.
"he hoped she'd be better in a couple of days"

verb: couple;

3rd person present: couples

past tense: coupled

past participle: coupled

gerund or present participle: coupling

1.
combine.

"a sense of hope is coupled with a palpable sense of loss"

join to form a pair.
"the beetles may couple up to form a pair"

2.
mate or have sexual intercourse.
"as middle-class youth grew more tolerant of sex, they started to couple more often"

#Discourse of the use of the word/phrase in this particular case

You

"how many would you like?"

Them

"just a couple."

When someone requests 'a couple of...' I respond with something similar to: 'How many do you want specifically?', which leads to the discourse of, 'A couple is two, a few is >2, several is <x' and so on.

I agree with the first two clearly stated definitions of 'couple', but in the informal use of a couple (eg. a depiction of a quantity) is not specifically two...nor is 'a few' three. How many specifically is several..?

I understand the semantics within the conversation. But, the expectation of understanding that two, and only two, is implied in the use of the phrase 'a couple' in a request; is ambiguously stating what one party desires. I'm the asshole now, just tell me how many you want.

And now...your thoughts, please.