Accidental Drug Use

I have a bit of a strange question.
I am about to start the clearance process for a Secret position. I hadn’t used drugs since trying marijuana in college, but a few months ago I ate a pot brownie without knowing it contained marijuana and proceeded to have a horrible and confusing night.

What do I say about this on my SF 85 or when asked about it? Do you think this is something that is going to get in the way of a clearance?

An SF-85 is filled out for low risk non-sensitive position, no clearance involved. If you are trying to get a clearance then you will have to provide mitigation as to why you were in a location/involved with individuals who were using illegal drugs, your use in college, other history, etc… so yes, it is definitely a concern.