Sindarin Insults & Threats
Insults 
Your
head is empty. ~ Dhôl chîn nâ cofn
or Dhôl chîn nâ lost.
Cowardly dog! ~ Hû ú-gaun!
Go kiss an orc! ~ Mítho
orch!
I hate you! ~ Chen ú-vilin!
Listen to my laughter! ~ Lasto
al lalaith nîn!
Much wind pours from your mouth. ~ Súlon
'wanna nîf chîn. (Lit. A big wind departs your face.)
Son of snakes! ~ Lýgion!
You disgust me! ~ Chen
fuion! (Lit. I feel disgust at you.)
You’re ugly and your mother dresses you. ~ Thiach
uanui ar naneth chîn chen hamma.
You are stupid. ~ Ech
uchand.
Orc lover! ~ Orvelethron!
Or feminine orvelethril!
You are hideous! ~ Thiach
uanui! (Lit.
You appear hideous!)
Threats
I hope the Ents will eat you! ~
Harthon in enyd chen medithar!
I want to hurl you into the fires of Mt. Doom!
~ Aníron chen haded min noer o Orodruin!
I'm going to hurl you into the fires of Mt. Doom!
~ Chen hedithon min noer o Orodruin!
Notes:
chen is the unattested accusative pronoun "you"
chîn is the unattested possessive pronoun "your"
ech is the unattested nominative pronoun "you"
mil- is a constructed verb "love"