Learn English – adjective for longing/yearning

From Introduction to the Grammar of English - Rodney D. Huddleston (1984)

The most straightforward type of adjectivalisation involves affixation, as in the formation of heroic.

It's true that when that feeling of longing and desire strikes, words just aren't adequate.

A drawn out mmmmmmmm-Mmmmmmmmm!" should be understood to be an expression of approval (with the emphasis on the 2nd Mmmmmmmm).

OR

A 2-note whistle, like a wolf call but kind of done under one's breath also conveys the same meaning of "oh boy!".

If those suggestions aren't enough, a long, audible inhale followed by an equally long and audible exhale have the same meaning - if performed as part of the same interaction with the friend and the object of desire.