Which function of nonverbal communication is at work?

Trey was planning a surprise party for Lynn, but when she asked him why they couldn't go out on Friday, Trey shifted his eyes, coughed, and stuttered when he said he already had plans. What did Trey's nonverbal communication do for Lynn

Question

Which function of nonverbal communication is at work?

Trey was planning a surprise party for Lynn, but when she asked him why they couldn't go out on Friday, Trey shifted his eyes, coughed, and stuttered when he said he already had plans. What did Trey's nonverbal communication do for Lynn

Vocaloid · Answer

Any ideas? Nonverbal = not using words, so what were some ways Trey communicated without using words? And what message could Lynn glean from his behavior?