Mind scent

A decent scent doesn't entail a good descent,
but a decent vocabulary may be tintinnabulary.
So sound to mind might be a tintin' scent.

A fixing in a fence

— You know, a fence in lattice theory, more precisely an $n$-element fence in lattice theory, is an ordered set $\{x_1,\ldots,x_n\}$ in which $x_1$ is greater than $x_2$, $x_2$ less than $x_3$, $x_3$ greater than the next one, etc., and $x_n$ greater or less than $x_{n-1}$ depending whether $n$ is odd or even, or $x_1$ less than $x_2$, $x_2$ greater than $x_3$, etc., and its Hasse diagram looks like a zigzag.
— I see. So a defense is quite the opposite, and its Hasse diagram looks like a zagzig.
— No offense, but no!
— Exactly! (You're so emphatic, I like that.)

Don't be irrational

— This is Math.
— Hi, Math. So, what's your phone number?
— RATIONAL... You wouldn't like to dial forever, right?
— But...
— I know, I know, I know,...

Joining the meeting

Behind a fence, where chains are more useful than antichains, a downset and an upset were eating an ambrosial De Morgan lattice salad when the downset said to the upset unexpetedly: “I feel very, very down, my friend, very, very down.” After a final big bite of that incomplete lattice salad, the upset dually said: “And that makes me maximally upset, my dear friend.”