덮치다 can be used for sexual expression. 1. rush to get laid. (usual one) 2. cuddle someone tight 3. kiss someone hard. these days, 덮치다 is also used for 2,3. but main usage is 1. so 꽉잡아 날, 덮치기 전에. it means "hold me tight. if you don't, I may rush into you."