sneak up (onsomeone)
phrasal verbwithsneakverb[always+ adv/prep]us/snik/past tense and past participlesneakedorsnuckus/snʌk/
toapproachsomeonequietlyandsurprisethatperson:
Overton sneaked up behindBrownandknockedtheballout ofbounds.
If aneventordaysneaks up on you, itarrivesbefore you arereadyfor it.