DY & Realist – You’re actually transgressing Lifnei Iver on yourself by going outside without blinders on. The reason the wording is “lifnei iver” is to teach us specifically in this instance that you should make yourself an Iver when it comes to chas vishalom seeing something inappropriate, make yourself unable to see and thereby unable to be nichshal.
See, I can make up a halacha or a drush just like you can!