...that cabinets and drawers are actually meant to be opened. Yikes! He hasn't shown any interest before today. Oh, and today just happens to be the day that he is starting to crawl for real...not just doing his belly flop scooch.
Thankfully, he just got into the tupperware cabinet, and he's happily playing with bowls as I research cabinet locks.  Anyone have a brand to recommend??  I have some cheap ones on cabinets with "bad stuff" but I don't like them.  ("Bad stuff"=soap, trashcans, ...all the really harmful stuff is stored on the top shelf of the linen closet) 
Re: LO has discovered...
https://www.safety1st.com/usa/eng/Products/Home-Safety/Latches-Locks/Details/477-48483-Adjustable-Multi-Purpose-Strap
Cabinets are prety much the only thing besides the stairs that we have child proofed. We have tried all different kinds, we like these the best. We use them on a few cabinets with harmful stuff and the main doors of our house when we are home, because DS1 can open the doors and we don't want him to let the cats out.