The past tense of "sneaked out" is sneaked out.
While "sneaked" is the past tense of the verb "sneak", the entire phrase "sneaked out" functions as a single past tense verb.
This is because the phrase describes a completed action in the past.
Here are some examples:
- She sneaked out of the house.
- They sneaked out to the party.
- The dog sneaked out the back door.