According to the search results, "nga" in TikTok does not have a specific meaning. The only result that mentions "nga" is from Urban Dictionary, which defines it as a sound that is made during an intense, nasty blowjob. Therefore, it is important to note that this definition is not appropriate for children or young adults. It is important for parents to monitor their childrens use of social media platforms like TikTok to ensure that they are not exposed to inappropriate content.