Having a random flashback of the events that took place while under the effect of some dank marijuana. Usually happens while sober, and the memory suddenly hits you out of the blue, even though you can't remember the rest of the night. Sometimes it's possible to piece together a whole night by putting together everyone's hashbacks.
When somebody else jacks your or others hashtags to promote there twitter page or product
Example of Hashjacking:
Omg check out this cool thing or a tweet full of hashtags
#NYCMarathon
#PrimarySchoolMemories
#Secondaryschoolmemories
#IveAlwaysWantedTo
To take something small, that doesn't quite qualify as a theft. Probably from the Danish "skæv" or the Dutch "scheef", both of which are pronounced similarly, meaning "askew, or not quite right'. To change an item's ownership without permission, but only something small and of little worth.
"I skeefed an apple off the neighbor's tree." "I skeefed some chips outta your bag when you looked away." "Don't skeef my chair when I go to the bathroom."