Hi MM,
A (possibly wrong) observation, but quite a simple point that may have validity:
Whenever you were growing up, and watching telly, and the subject matter veered towards adult material, I guess it is possible your dad would have become more verbose / fidgety / enthralled.... and I imagine that simultaneously you would have felt silenced and worried and possibly disgusted...
This, I guess, would have carried on for YEARS.
It is possible you have formed an association in your mind between this sort of imagery and the feelings of revulsion I alluded to above... the end result is that when an individual (say dh, who let's assume is 'normal') watches TV that builds up to an adult scene (however mild perhaps), YOU start to feel nervous / embarassed / angry / upset...
This doesn't 'solve' your problem, but being able to look at this possible association and reflect on it, and then to work on KNOWING that your dh / another bloke looking at TV / posters in the street etc. ARE NOT following the same thought processes and behaviours as your dad... might be key to integrating a more 'normal' reaction to this kind of stuff.
I hope I'm not being a patronising git, or insulting, and that what I've written is perhaps helpful.
If you would like to get to a 'more normal' space in terms of your attitude and behaviour (and I'm not saying you should, or that that would be preferable), you may find some desensitising exercises, or creating new associations (perhaps under the guidance of a CBT / councillor / interested friend / dh) may help.