What breaks your wudu?

The things that break wudoo' are:
1 - Any discharge from the front or back passage (urine, stools, wind, etc.), except for wind emitted from a woman's front passage - that does not break wudoo'.
2 - Emission of urine or stools from anywhere other than the urethra or anus.
3 - Losing one's mind, which may mean losing it altogether by losing one's mental faculties, which is insanity, or by losing it temporarily for a certain length of time for some reason such as sleep, unconsciousness, intoxication, etc.
4 - Touching one's penis, because of the hadeeth of Basrah bint Safwaan, who heard the Messenger of Allaah (peace and blessings of Allaah be upon him) say: "Whoever touches his penis, let him do wudoo'." (narrated by Abu Dawood, al-Tahaarah, 154. al-Albaani said in Saheeh Sunan Abi Dawood, no. 166, it is saheeh).
5 - Eating camel meat, because of the hadeeth of Jaabir ibn Samurah, who said that a man asked the Prophet (peace and blessings of Allaah be upon him), "Should we do wudoo' after eating camel meat?" He said, "Yes." (Narrated by Muslim, al-Hayd, 539).
It should be noted that if a man touch a woman's body does not break one's wudoo', whether that is done with feelings of desire or otherwise, unless anything is emitted as a result of that touching.
See al-Sharh al-Mumti' by Ibn 'Uthaymeen, vol. 1, p. 219-250
Fataawa al-Lajnah al-Daa'imah, vol. 5, p. 264

Source: Islam Q & A

http://www.islam-qa.com/en/ref/14321/