As J says above, they are 'polite' phrases which first appeared in the (supposedly) prim and proper days of the late Victorian age and specifically thought suitable for nursery-talk.
in the hotel i used to work in , im going to the toilet took on a whole new meaning .
no.1 & no.2 , as above
no.3 a combination of both
no.4 cant stop now , or will shat myself
no.5 what i ate last night ,here it comes
no.6 you dont want to know ( back in 20 mins )