One bit of information I discovered last year is that the p-trap can provide a breeding ground for fruit flies. I cover or close the drains on sinks I don't use often. I doubt, squirrels c an get through but I do know rats can get into the sewer drain and come up in the toilet.
 JackPedigo
                                                
                                                Level 9
                                                Jan 31, 2019
                                            
                                                
                                                    JackPedigo
                                                
                                                Level 9
                                                Jan 31, 2019                                            
                                        ??? I think you missed the point of the post?
@SkotlandSkye I know it was supposed to be a joke but I just thought I'd add a little 'fun' of my own, sorry.