Formation: coulda = could + have

Usage: I coulda eaten one more donut.

Meaning: I could have eaten one more donut.

Formation: mighta = might + have

Usage: I mighta gone to the party if she wasn't going.

Meaning: I might have gone to the party if she wasn't going.

Formation: musta = must + have

Usage: She musta been really tired after working so many hours.

Meaning: She must have been really tired after working so many hours.

Formation: shoulda = should + have

Usage: You really shoulda come with us.

Meaning: You really should have come with us.

Formation: woulda = would + have

Usage: I woulda come if I wasn't working.

Meaning: I would have come if I wasn't working.