Tittenfick is a very multifunctional German word.
The literal translation means Tittie Fuck.
In some regions in Germany it's also used to show different kinds of emotion, no matter if positive or negative.
It's also possible to say it instead of a word you just forgot at the moment.
Krasser Tittenfick! Hast du dieses geile Auto gesehen?
(What a Tittenfick! Have you seen this great car?)
Tittenfick! Sie haben schon wieder ein Tor gemacht!
(Tittenfick! They scored a goal again!) Tittenfick can be meant positive as well as negative. It just depends on what team you support...
Mach den Tittenfick (=computer, TV, was auch immer...) da mal aus!
(Come on and shut down this Tittenfick (=computer, TV, whatever...)!