go to the bathroom before and then clean it with soap.

Well it's completely possible that feces came out with the other man's penis. That's pretty normal, considering your anus and colon is full of feces.

The best way to prevent such an accident again is to make sure you've already gone #2 recently. If you're feeling very paranoid, you can buy a cleansing enema kit and completely clean the inside and outside of your anus and lower colon.

if i were you...first of all i wouldnt worry and i wouldnt be so0 hard on urself...caca happens...n0 pun intended...but it does.
just because this happened once does not mean its going to happen everry time.its probably not goin to even happen again. it probably just happened to be a bad timing sort of thing. dont worry!
but if u are relle worried, which u seem to be..b4 u start u know fo0ling around and watever go to the bathroom...if u feel even the slightest urge to go #2 then deff do it b4..make sure u clean well. and then hope for the best... and if u relle are serious about this i agree with the other person..use an enema kit. but if ur not serious and u are worried. tell him that ur not relle comfortable. thats wat i told my bf and he knows im not gonna do it. does he ask me? sure. does he want to? yes. but every time i tell him no because im not comfortable with it nor do i like it..well i hope i helped u out somehow. go0d luck and let us know wat happens! =]