Does Laughing Break Wudu?
Question

Does laughing invalidate Wudu even though the person is not actually praying; rather he is getting ready to pray?
Praise be to Allah.Does laughing break Wudu?
There is no difference of opinion among the scholars that laughing outside of prayer – even when one is getting ready for prayer – does not invalidate Wudu.
Ibn Al-Mundhir (may Allah have mercy on him) said: “The scholars unanimously agreed that laughing outside of prayer does not invalidate Wudu and does not require one to do Wudu again.” (Al-Awsat, 1/166)
An-Nawawi (may Allah have mercy on him) said: “They [the scholars] unanimously agreed that laughing out loud outside of prayer does not invalidate Wudu.” (Al-Majmu`, 2/61)
Does laughing invalidate prayer?
The scholars unanimously agreed that laughing when praying invalidates the prayer .
Ibn Al-Mundhir (may Allah have mercy on him) said: “They unanimously agreed that laughing when praying invalidates the prayer.” (Al-Ijma`, p. 3)
What is meant by laughing here is laughing out loud
Ibn Qudamah (may Allah have mercy on him) said: “We do not know of any difference of opinion concerning that.” (Al-Mughni, 2/451)
Shaykh Al-Islam Ibn Taymiyah (may Allah have mercy on him) said: “Laughing out loud, in which one makes a loud noise, is contrary to the dignity of prayer and to the focus and humility that is required in prayer. Moreover, it shows disrespect towards the prayer, makes a mockery of it and is contrary to its purpose, so the prayer is spoiled by that.” (Majmu` Al-Fatawa, 22/617)
Does laughing out loud in prayer break your Wudu?
From the above, it is clear that the difference of opinion among the scholars has to do with laughing out loud in the prayer and whether Wudu is also invalidated by it, or not.
The correct view, which is that of the majority of scholars, is that it does not invalidate Wudu, because there is no evidence to indicate that it does invalidate it.
Jabir ibn `Abdullah (may Allah be pleased with him) said: “If someone laughs whilst praying, he must repeat his prayer, but he does not have to repeat Wudu”. (Narrated by Ad-Daraqutni, 51 and by Al-Bukhari in a Mu‘allaq report)
Ibn Hajar (may Allah have mercy on him) said: “It is proven to be authentic, but it is the words of Jabir.” (Fat-h Al-Bari, 1/280)
Shaykh Al-Islam (may Allah have mercy on him) said: “There is no narration from any Companion to suggest a different view. Moreover, it does not invalidate Wudu outside of prayer, so by the same token [it does not invalidate Wudu] in the prayer.”(Sharh Al-`Umdah, 1/324)
An-Nawawi (may Allah have mercy on him) said: “Our view and that of the majority of scholars is that it does not invalidate Wudu. … This is the view of the majority of the Tabi‘in and those who came after them.
Al-Bayhaqi narrated that Abu Az-Zinad said: I met some of our well-versed scholars whose view is decisive: Sa‘id ibn Al-Musayyab, ‘Urwah ibn az-Zubayr, Al-Qasim ibn Muhammad, Abu Bakr ibn ‘Abd ar-Rahman, Kharijah ibn Zayd ibn Thabit, ‘Ubaydullah ibn ‘Abdillah ibn ‘Uqbah, Sulayman ibn Yasar, and many other respectable scholars, who say that laughing invalidates the prayer, but it does not invalidate Wudu.
And he said: There is no proof at all to suggest that Wudu is invalidated by laughing.” (Al-Majmu`, 2/60)
The Hadiths which say that laughing invalidates Wudu are weak and none of them are sound.
An-Nawawi (may Allah have mercy on him) said: “All of them are inauthentic and flimsy, according to the consensus of the scholars of Hadith.” (Al-Majmu`, (2/61)
To sum up, laughing does not invalidate Wudu, whether that happens when praying or outside of prayer.
For more details, please refer to the following answers: 755 , 87749 , 22170 .
See also these categories: 
Things Which Invalidate the Prayer
Nullifiers of Wudu
And Allah knows best.