One of the most common reductions is the word “and”, which is reduced to “n”. So, in spoken English, “a burger and fries” sounds like “a burger n fries”

Waddaya mean we ain’t gonna get the project?

I know what you’re thinking – this sentence is full of mistakes! Those words don’t exist in English. And what happened to the verbs? And the pronouns? The truth is, you’re absolutely right – you’d never see this sentence in written English, except in a few special cases, like a movie script dialogue, or the lyrics to a particular song. Think Michael Jackson’s “Wanna be startin’ somethin’”, or the Spice Girls’ “Wannabe”.

In spoken English, especially in American English, native speakers “fuse” words together, or just leave out certain vowel or consonant sounds, or both. When sounds in words are changed or left out, we call this a linguistic reduction, or simply, reduction. English learners take care to pronounce words carefully and learn all the intricacies of English sounds, but as in all languages, native speakers don’t do this.

Another extremely common reduction is changing “what do you / what are you” in questions to “waddaya”, as in “waddaya want?” or “waddaya doin’?”. Often, this is put together with “want to”, which is another reduction. So, the question “What do you want to do?” becomes “Waddaya wanna do?” and “What do you want to have for lunch?” becomes “Waddaya wanna have for lunch?”

Other very habitual reductions include the combination of modal verbs with “have”:

Could have > coulda
Should have > shoulda
Would have > woulda
Might have > mighta
Must have > musta

You need to know some of these reductions because native speakers will use them, and it will help you to understand them. If you can use them sometimes, you’ll sound more natural.