When you instant message someone the second you see them sign on, not even allowing them to put their away message up; thereby creeping them out a bit
The other day I had to aimbush one of my classmates, because sometimes she signs on and goes to take a shower. She might not have gotten the message for hours.
by Ben Faulding March 08, 2006
v. To send an instant message at such an inopportune time that the recipient quickly replies with an aborted fragment of whatever he or she happens to be typing.
You totally aimbushed me! I hope you enjoyed reading the last three words of my third body paragraph!
by Andrew Erickson June 30, 2005
To hide offline on an Instant Messenging service until a specified person comes online, before immediately coming online after they do in order to force a conversation.
'Omg Steph totally aimbushed me last night, this is the fifth time she's done it this week'
by Jimblywimbly May 24, 2007