Whisk the mayonnaise and Greek yogurt in a medium bowl until smooth.
Stir in curry powder, garlic powder, salt, pepper, and lemon juice until evenly blended.
Fold in the chopped dates and green onion.
Splash in warm water a little at a time until the dip loosens to a creamy, scoopable texture.
Cover and chill 15 minutes for the flavors to meld, then serve.