Jumping can mean two things, depending on whether it is used to enter or exit a bath. It is more broadly called vaulting if the hands are used to assist the feet in propelling the body upward by pushing down on something, usually the rim of a tub.
When someone is jumping in to a bathtub is often done to show enthusiasm for bathing. It is more dangerous than stepping in carefully, as you can slip. It often causes splashing and temperature-testing usually does not precede it, which could shock someone with an unexpectedly hot or Cold Bath, leading to freezing or Burning.
The expression "jump in the bath" may also be used to indicate a quick bath, without the person literally jumping in.
- Date A Live episode 4 (need proper pic showing jumping)
- Matua Jona from Crusher Joe (need proper pic showing her jumping)
- Yatterman episode 40 Doronjo (pics missing)
2002 (May 25) three girls do it in Tokyo Mew Mew episode 8
When someone is jumping out of a bathtub, they are usually trying to get out in a hurry. This could be for various reasons, like trying to answer a phone call, being unable to stand the temperature, being peeped at, or someone entering the bath without permission.
When someone is jumping on during a bath, it is presumably during a Group Shower or related and a kind of friendly gesture. This can also be a form of attack or an accident though.