Just type jk slowly.

Also see [1]:

  :help timeoutlen

and

  :help ttimeoutlen

[1] - http://vimdoc.sourceforge.net/htmldoc/options.html#%27timeou...

Alternatively, you can type jjkak (insert a j, exit insert mode with cursor on the j, enter insert mode one character to the right, insert a k).

Yeah, man. That shit freaked me out real bad. I also started eating salads and stopped hunching so much at the monitor.

Just like in the shell, anything prepended with Control+V will be input literally, so you can type Dij<C-v>kstra.