The stop in syllables that end in a homorganic nasal-plus-stop cluster (in English, these clusters are /mb, mp, nd, nt, ŋɡ, ŋk/) is often elided. Word-final /-mb/ and /-ŋɡ/ never occur in Modern English, for example, although their dumb Middle English spellings hang around.
Final /-nd/ does occur, though not always, but it's frequently neutralized with /-nt/, especially after a stressed vowel and preceding an unstressed one. As in twenty.
This interacts with the neutralization of /d/ and /t/ in the same environment; in American English, both go to [ɾ], as in betting and bedding, which differ -- if at all -- only in the allophonic vowel length of stressed /ɛ/ in the first syllable of bedding.
Upshot: In American English, /'twəni/ is the normal pronunciation, /'twɛni/ is somewhat more formal and careful, and /'twɛnti/ is fastidiously careful.
Quite similar is
have/get one's nose/snout in the trough
British disapproving
to be in or get into a situation in which one is getting or trying to
get a lot of money
{Merriam-Webster}
'He's got his nose in the trough' could be applied to any person over-eagerly procuring money, but is almost always used for illegal or at least dodgy practices.
Best Answer
It is perfectly acceptable to say "give me half of that". In English, "half" in understood on its own to mean "one of two equal parts of something".
To put it another way:
Saying "give me one half of that" is redundant. It's equivalent to saying "give me one of one of those two equal parts of that."