To roger a woman up the rear who is under 18 but over the age of consent, this was illegal in the uk due to homosexuality laws until recently but now chuffucking is well practiced fun
Marc: dude i rammed this girl the other day Marc 2: Dude no way!!
Marc: Yeah and then she let me chuffuck her shit was so cash Marc 2: no way i was chuffucking your mum last night too
Marc: ...
Chuck is a metaphor for all the people in your life that you think you have under your control. Then, when you least expect it, BAM!! You get chuckfucked, leaving you confused, embarrassed, and slightly in awe of the power that just got released upon you.