sneak

For the verb: "to sneak"

Simple Past:	sneaked, snuck
Past Participle:	sneaked, snuck

Concise Oxford English Dictionary © 2008 Oxford University Press:
sneak/sniːk/

▶verb (past and past part. sneaked or informal, chiefly N. Amer. snuck)

• 1 move, go, or convey in a furtive or stealthy manner.

  ■ stealthily do or obtain: she sneaked a glance at her watch.

• 2 Brit. informal inform someone in authority of a person's misdeeds.

▶noun informal

• 1 Brit. a telltale.

• 2 a furtive person.

• 3 N. Amer. short for sneaker.

▶adjective acting or done surreptitiously: a sneak preview.

– origin C16: prob. dial.; perh. rel. to obs. snike ‘to creep’.

usage: The standard past form of sneak is sneaked. An alternative past form, snuck, arose in US dialect in the 19th century. Although snuck was formerly regarded as non-standard its use has spread in the US, where it is now regarded as a standard alternative to sneaked in all but the most formal contexts.