If another creature becomes a copy of, or enters the battlefield as a copy of, the token, that creature will copy the creature card the token is copying, except it will also have haste. However, you won't sacrifice the new copy at the beginning of the next end step.

If the copied creature has {X} in its mana cost, X is 0.

Any enters-the-battlefield abilities of the copied creature will trigger when the token enters the battlefield. Any "as [this permanent] enters the battlefield" or "[this permanent] enters the battlefield with" abilities of the copied creature card will also work.

If Kiki-Jiki's ability creates multiple tokens due to a replacement effect (such as the one Doubling Season creates), you'll sacrifice each of them.

If a copied creature is copying something else, the token you create will use the copiable values of the target creature. In most cases, it will just be a copy of whatever that creature is copying.

The token copies exactly what was printed on the original creature (except that the copy also has haste) and nothing else (unless it's copying a creature that's a token or that's copying something else; see below). It doesn't copy whether the creature is tapped or untapped, whether it has any counters on it or Auras and/or Equipment attached to it, or any non-copy effects that changed its power, toughness, types, color, and so on. Most notably, if the target creature isn't normally a creature, the copy won't be a creature.

If a copied creature is a token that isn't a copy of something else, the copy copies the original characteristics of that token as stated by the effect that created it.