Those dicks are easy, you need to keep back and slightly above them if you're planning on shooting. If you want to dodge then just nip under them - handy on the 1st cock tanks part.

TBH the goatse-cocks on the 1st level are the hardest part, they take a lot of blasting and when there's a few on screen it gets a bit bullet-hellish.

The 1st level's got a great points whore part though. Blast the 3rd boss until it starts spraying shit at you then keep right back & blast the shit to boost scores, using your dogbreath you can get over 100k just from the shit.