Southern Thai in red:

อิๆๆๆ บอกแล้วให้แขบลบ

ก่อนอื่นต้องขอแสดงความยินดีเป็นอย่างแรงที่เพื่อนมีฟันเต็มจอแล้ว สวยจังหู ไม่มีเค้าโครงกิ่งเข้ คนเดิมเลย

Can anyone help?

Kep means quickly ie do it quickly, second word, lop means something like remove, delete, erase. (or so my cook thinks, I didn't recognize them)

She's not sure on the second one. What part of the South is this from?

Thanks, sbk. I'm not sure which part, sorry. I actually thought this was Isaan or northern Thai at first, but was told it was southern Thai.

อิๆๆๆ บอกแล้วให้แขบลบ

Given sbk's cook's explanation, this would be something like 'Hihihi, I told you to erase it quickly.'

(Leaves the feeling that C, a third person, has read or seen something they were not supposed to read or see. Person A now jokingly reminds B [who wrote this, whatever it was] that A told B to erase it quickly. A case of 'I told you so'.

Dunno about the second sentence, there are two things I don't understand, partially what is in red, and also เพื่อนมีฟันเต็มจอแล้ว. "My/His etc] friend has X [teeth?] all over the screen.

The literal translation of ฟัน is 'tooth' or 'teeth' but here I am wondering if ฟัน might be a deliberate or dialectal spelling of ฝั่น which is slang for 'to penetrate; have intercourse with', which would give 'had a porn picture or movie all over the screen' [i.e. when C came into the room or turned on the screen]?

Just guessing.

That's great input, meadish_sweetball. (Love your handle!) For the second one, the long line, a Thai friend of mine suggests that someone is sarcastically/jealously congratulating someone's friend for having dental work done, which has made their teeth สวยจังหู now and they don't look like the "old you" (คนเดิมเลย) anymore, but my friend doesn't know what ไม่มีเค้าโครงกิ่งเข้ means here.

หลบ in southern Thai means "to return" (like กลับ in standard Thai), so I wonder if the ลบ on the first line is supposed to be that instead. If so, the meaning would be like "I told you to come back/come home quickly."

Yes, she was confused by the teeth reference too. But she is a nice traditional girl so if its obscene she may not have heard it

That's great input, meadish_sweetball. (Love your handle!) For the second one, the long line, a Thai friend of mine suggests that someone is sarcastically/jealously congratulating someone's friend for having dental work done, which has made their teeth สวยจังหู now and they don't look like the "old you" (คนเดิมเลย) anymore, but my friend doesn't know what ไม่มีเค้าโครงกิ่งเข้ means here.

This word เค้า keeps turning up, I have been saying 'evidence' it also means features and โครง is framework /skeleton sort of thing so If it is about teeth 'no trace of the features of crocodile like the original'.

.

Thanks to everyone for the different analysis and inputs. I think I got it sorted now. I'm grinning like a crocodile at feeding time!