The phrase "Mr You Know Who" in the context of Ireland around 199 or the 1990s appears to refer to an unnamed or discreetly referenced political figure or minister, often used when the identity is widely known but not explicitly stated due to controversy or sensitivity. This term was used in Irish political discussions and media to refer to certain ministers or politicians without naming them directly, usually because of scandals or political sensitivities

. There is no specific individual directly identified as "Mr You Know Who" in the search results, but the term was common in Irish political commentary, especially during times of political scandal or corruption in the 1990s and early 2000s

. If you are referring to a notable Irish political figure from around the 1990s, Charles Haughey was a dominant and controversial figure in Irish politics during that era. He served multiple terms as Taoiseach (prime minister) and was involved in several scandals, earning a reputation that might have led to euphemistic references like "Mr You Know Who"

. In summary, "Mr You Know Who" is a colloquial or euphemistic way to refer to a known but unnamed Irish political figure, often linked to controversy, particularly in the 1990s. Charles Haughey is a prominent example of a figure from that period who might fit this description. However, no definitive identity is provided in the sources for the exact phrase "Mr You Know Who"