Laughing out loud does not invalidate ablution at all, but it has specific conditions: 1. The person praying must be of age; even if a child laughs out loud, their ablution is not invalidated because it is not a wrongdoing on their part. 2. The person praying must be awake; even if they fall asleep during prayer in any position, laughing out loud does not invalidate their ablution. 3. The person praying must be either in a state of ablution or performing dry ablution (tayammum); even if they laugh out loud during a prayer that requires a full wash, it invalidates the prayer, not the wash. 4. The laughter must occur during a prayer that includes bowing and prostration; this is to distinguish it from the funeral prayer and the prostration of recitation, where laughing out loud does not count as an event, but rather invalidates what was laughed at. Similarly, outside of prayer, it is even more so; because when the text is contrary to analogy, it is limited to its specific case, which is the absolute prayer, and thus it is restricted to it, not being an event in other cases. See: Sharh al-Wiqayah, 2: 33-34, and Tabyin al-Haqaiq, 1/ 11, and Fath Bab al-Inayah, 1/ 68, and al-Ikhtiyar, 1/16-17, and Mukhtalif al-Riwayah, p.344-345.