Ha-ha only joking
So I'm having a pizza delivered to your house right now.
... but that wasn't funny.
|HHOJ/K||Ha-ha, only just kidding|
|HH1/2KO||Ha ha, half-kidding only|
|JFK||Just freakin' kidding|
|UG2BK||You've got to be kidding|
HHOJ is a less-common variant of JK. People use it to let others know that a previous message they sent was just a joke.
After receiving HHOJ, you may or may not find the sender's "joke" funny. If you do, you can reply with HHSF or TF. If you don't (which is more typical), you can reply with a sarcastic SFF.