The phrase "come snuff" can refer to a variety of things, from inviting someone to take in a whiff of tobacco to encouraging someone to step up their game. However, if you're looking for some synonyms for this phrase, you could try using the expressions "take a whiff," "smell the roses," "sniff around," or "breathe in deeply." Additionally, you could use idioms like "turn up the heat," "step up to the plate," or "take it up a notch" to convey a similar sense of encouragement or challenge. Ultimately, the best synonym depends on the context in which you're using "come snuff," but these options should provide some inspiration for conveying the same message in a different way.