You guys is a mashup of two words, you and the second person plural. It’s used in informal conversation in North America. The first part is an adverb, referring to the person, while the second part is a prepositional phrase. A variant is y’all, which is used in African American Vernacular English. Historically, you only occurred in the dative case.
Similarly, youse is a nod to the Irish-American. Y’all is used in the southern United States. They are not synonymous, though. Both words have a corresponding counterpart in the north. As such, youse is more common in urban centers in the northern U.S. Interestingly, youse is not necessarily the best way to say youse. However, youse is the more likely alternative, especially in a sentence with youse as the verb. In some cases, the word is substituted for ye, as in “youse y’all”, thereby creating a more nuanced meaning. Ultimately, youse is a confusing name, with the plural version being used by more people than the singular one. For example, youse is often used as a noun to mean ‘ones or one’s mates’, and youse is used as a noun to mean a couple.
While you guys and youse aren’t synonymous, they are similar enough to be considered a good start. On the flip side, you and youse aren’t quite as symmetrical, with youse being more common in educated speech. There are also notable exceptions, such as youse as a noun, and youse as a verb. Despite this, you isn’t an adverb, but rather a plural verb. Thus, it’s not too difficult to imagine a you and youse announcing themselves as a pair.
Aside from the usual suspects, you and youse are not as synonymous as you and you, or you and you. Youse is most commonly used in a regional dialect of the language, while youse is the unofficial name for a linguistic sex, notably in Ireland. Historically, youse was used only in the dative case, but has since been adopted as a second-person plural in formal speech. This usage has been a source of contention, as it is not necessarily the most logical use of the word.
Although the ole dandy you is a singular omission, it does have the aforementioned novelty adverb attribution. Moreover, youse can be a fun one-word adverb, and the second-person plural is often the sex-friendly answer. If you want to make this word work for you, don’t let the gendered version of you hold you back. And if you’re interested in making the move, you’ve got to do it with a big ole smile!
Lastly, you should also consider a you-and-youse test of the quality of your aforementioned adverb. A study done by the University of Wisconsin-Madison found that gendered versions of you were less likely to be regarded as a good word, while youse is more likely to be taken as a compliment.