I heard 咪咪 means boobs in a slang term, is this true?

It is but afaik not being used much anymore. 奶子 or 欧派（from おっぱい）is more common.
HiNative is a global Q&A platform where you can ask people from all over the world questions about language and culture. We support over 110 languages.

Orion Magazine - Altar Call for True Believers

13 Portuguese Slang Words to Speak Like a True Brazilian - MosaLingua

Profiles in Diversity Journal Second Quarter 2022 by Diversity Journal - Issuu

the Secret Language of Irish Travellers - Donegal Traveller's Project

The 100 Best Songs of 2021

The Slang Dictionary, by John Camden Hotten--The Project Gutenberg eBook

Do you use the word buzz to mean spread on twitter?

Mary J. Blige on the Beauty of Vulnerability - The New York Times

That's a no from me : r/ShitMomGroupsSay

The Turkish word for meme is boobs so what do turkish people call memes in Turkey so they are not running around saying breasts? : r/Turkey

40 brilliant idioms that simply can't be translated literally

101 Words for Boobs – Curvy Kate UK

Mariguano: A Novel: 9781937875329: Ochoa, Juan: Books