"You'll to have to work in your catch phrases" vs. "You could have to work on your catchphrases."

[Uncanny]

Which version makes sense:

Version 1

A (in a stilted manner): As you'd know if you were an amputee, you can still get an itch in the bit of you that's been cut off.
B: You'll to have to work in your catch phrases.

Version 2

A (in a stilted manner): As you'd know if you're an amputee you can still get an itch in the bit of you that's been cut off.
B: You could have to work on your catchphrases.

What is there in the last line that makes the audience laugh?

/ from WILTY S03E04 /

 

[emsr2d2]

Neither is grammatically correct.

You'll have to work on your catchphrases.
You have to work on your catchphrases.
You might have to work on your catchphrases.

I'd be more likely to say "You need to work on your catchphrases".

Without knowing what's said before A's line, it's impossible to say why an audience would laugh at the exchange.

 

[Uncanny]

Neither is grammatically correct.

You'll have to work on your catchphrases.
You have to work on your catchphrases.
You might have to work on your catchphrases.

I'd be more likely to say "You need to work on your catchphrases".

Without knowing what's said before A's line, it's impossible to say why an audience would laugh at the exchange.

Here is the subsaga version of the subtitles:

When you see a bunch of flowers, you think they're silently going, "My feet hurt! Ow, my feet hurt!" 0:03:32 0:03:39
She said "Where the hell are my feet? My ankles are killing." 0:03:39 0:03:42
As you'd know if you were an amputee, you can still get an itch in the bit of you that's been cut off. 0:03:42 0:03:47
You'll to have to work in your catch phrases, David. 0:03:47 0:03:50

 

[emsr2d2]

Here is the subsaga version of the subtitles:

When you see a bunch of flowers, you think they're silently going, "My feet hurt! Ow, my feet hurt!" 0:03:32 0:03:39
She said "Where the hell are my feet? My ankles are killing." 0:03:39 0:03:42
As you'd know if you were an amputee, you can still get an itch in the bit of you that's been cut off. 0:03:42 0:03:47
You'll to have to work in your catch phrases, David. 0:03:47 0:03:50

Thank you! Now it makes much more sense (although I have no idea what a "subsaga" version of anything is).
Anyway, the whole thing starts off as a joke - a flower complaining that her feet hurt, then realising she has no feet (roots) and her ankles must be hurting instead. It's not the world's greatest opening to a joke but it's vaguely amusing. However, the amusement level drops to zero with the line about an amputee. That's basically someone ruining what might have gone on to be a very funny joke by throwing in a statement of fact about phantom pain. The joke is ruined. Instead of a great punchline ("catchphrase" is the wrong choice of word), the joke comes to a crashing halt. That's why someone tells that person that they need to work to make their punchlines better.