Paka

Used in Sinhala.
Penis (swear). Closest English equivalents would be dick and cock.

Variations:
Pakaya (used to describe a person)

"Ara pakaya."
Sexual ways it can be used which I am not gonna type out.

Oyaa

Used in Sinhala.
You. Casual and friendly way of saying 'you'.

Plural:
Oyaalaa/Ougollou

"Oyaata kohomada?"
"Oyaalaa ho'ndin da?"

Huththa

Used in Sinhala.
It literally means vagina (with an unstresed 'a' at the end like in 'about'), but variations of it are used as a general insult with the closest English translation being 'cunt'.

Variations include:
Huththa (with a stressed 'a' like in 'art' and is typically used for males)
Huththi (mostly used for females)
Huththo (used when you're directly addressing someone)
Huththak (a singular vagina, or a fucked up/annoying situation or thing)

"Ey huththa mala vaathayak ado."
"Moko thota bari huththo?"
"Hena huththak patangan nathuwa hitapiya!"

Katavahapiya

Used in Sinhala.
Shut up (ruder version of kata vahaganna and katavahapan).

"Katavahapiya ballo."
"Tho huththo, katavahapiya!"

Puka

Used in Sinhala.
Arse/ass.

"Puka gahaganin!"
"Thaaththata puka arapang!"

Kata vahaganna

Used in Sinhala.
Shut up.

Ruder Variations:
Kata vahagannawa
Kata vahaganin

"Kata vahagannawa ko ane."
"Kata vahaganin oi!"

Tho

Used in Sinhala.
You. The most affrontive and offensive way of saying you in Sinhala.

Plural:
Thopi

(*Note: The singular word 'tho' has a long 'o' sound, but this is shortened when changing the word's form to the plural or possesive 'thota')

"Thota pissu da oi?"
"Mang thopita kisi samaawak den na!"