Splashing someone with a puddle can be considered a form of assault or harassment, depending on the circumstances and the severity of the act. While it might seem like a harmless or playful action, it can be perceived as offensive or even dangerous, especially if it affects the person's clothing, belongings, or well-being.

Whether it is illegal or not depends on the jurisdiction and local laws. In some places, such an act could be considered a criminal offense, while in others, it might be treated as a civil matter. Additionally, the intent behind the action and any resulting harm or distress caused to the individual could also be taken into account.

It's essential to be aware of the laws in your specific location and exercise common sense and consideration for others to avoid legal issues or conflicts. If in doubt, it's best to refrain from engaging in actions that may potentially cause harm or distress to others.