You could take a rather large dose of an opiate/iod which would contrict your pupils possibly balancing them out? How often do you come into contact with cops with dialated pupils (honestly)?
once...
driving while rolling, getting pulled over for a head light out....
he thought i was drinking (fuckin wrist band from the venue i was at before leaving), so he made me follow a little blue LED light on the end of a pen thing with my eyes....
he asked nothing about the size of my pupils, but then again i never get the blacked out disco pupils some get, sure my eyes dilate but with a pretty bright light source they still contract a bit....
i knew what he was looking for and managed to follow the light well enough without my eyes wiggling to get out of it....
i got really fucking lucky, he pulled me over litterally 15 feet from my drive way and i had told him i was comming from the city so i guess he assumed that i could make it the last 15 feet with 1 head light and just told me to get it fixed the next day.... i had to eat the bean i wanted to save because i was already up to 2, but the 2nd had not quite hit and when i saw the blue lights i ate the 3rd....
when i got into my house i called a friend, gave directions to my house to be picked up, and was rolling uncomfortably hard in my room until i got picked up....
as far as excuses, some types of visine dilate some peoples pupils temporarily (says so on the bottle)....
eye doctor
messed up blood sugar, i know diabetics who's pupils are always huge....
if it were a cop you could possibly try the "i am prescribed adderal and it dilates my pupils" im not sure how much they would try to argue with you about that though or ask for proof...
i don't know, never really was asked by my parents about it.... if my mom had said "your pupils are huge, are you on drugs?" i just would have said "well i can hardly see yours, lay off the vicoden and get back to me"
thankfully i never had to have that conversation....