Where is my wiener?

Max has been asking a pretty wide array of questions lately.  I know this is normal 4ish year old behavior but he has expanded on just the simply "why".  The other day he wanted to know where he came from.  I told him my tummy.  He then proceeded to ask me where every person he knew came from.  When he ran out of people he knew he started asking about where the pets came from.  We were on the way to Ohio at the time.

Yesterday he asked me where my wiener was.  I told him I didn't have one.  And of course he asked why.  I told him mom's don't have wieners.  I thought that satisfied him, its not the only time he has asked that question but this was different, he is a little older and he then asked how I peed.  I really need to start locking the bathroom door.