Sneaked vs. Snuck
The "Rule": "Snuck" is not a proper word.
The Reality: There's no need to sneak around "snuck."
"Sneaked" or "snuck"? Your English professor might prefer "sneaked" as the past tense of "sneak," but most people in the US use "snuck."
According to the American Heritage Dictionary, the Americanism "snuck" probably arose in the 19th century, imitating the pattern set by stick/stuck and strike/struck.
Widespread use of snuck in the US has become more common with every generation, and it is now used by educated speakers in all regions. "Snuck" occurs frequently in fiction, in journalism, and on radio and television, whereas "sneaked" is more likely in highly formal writing.
In fact, "snuck" is the only spoken past tense and past participle for many younger and middle-aged persons of all educational levels in the US and Canada. "Snuck" is so widely used by professional writers and educated speakers now that it can no longer be considered nonstandard. As Brian A. Klems of Writer"s Digest put it, "'Snuck' has sneaked its way into our American lexicon."
Snuck: Cringe-inducing or totes OK?