OTOH is a piece of internet slang that's been around forever, but it still pops up on Reddit and Twitter to this day. So what does OTOH mean, where did it come from, and how do you use it?
On the Other Hand
OTOH is a direct abbreviation of the real-world phrase "on the other hand." It's used when someone wants to consider another side of a discussion or argument.
While asking friends where to meet for lunch, someone might say, "Hardee's has the best fries!" You might reply, "I like Hardee's, but OTOH, it's 20 minutes away from my house." Again, OTOH is a direct abbreviation, so you can use it anywhere that you might use "on the other hand."
It's worth mentioning that OTOH can also stand in for "on the one hand," which some people use in place of "on the other hand."
Etymology
OTOH isn't the most popular piece of internet slang, so it's difficult to track the word's origins. The oldest example we can find of OTOH appears on a mid-90s Grateful Dead fan page, which is available in a UC Berkeley archive. (This archive includes some other gems, like MSWS---Men Smart, Woman Smarter.)
Anyway, OTOH first appeared on the Urban Dictionary in August of 2003, and it has maintained steady popularity on Google Trends (a service that tracks popular search terms) since 2004. You'll still find the term on Reddit, although not as much as some similarly niche abbreviations, such as FTFY or DAE.
How Do You Use OTOH?
You can use OTOH wherever you might use the phrase "on the other hand." It follows the same grammar rules as its parent phrase, so you don't have to worry about learning any weird new practices. That said, it's worth noting that OTOH can be written in all caps or in lowercase.
Need an example of OTOH? Let's say you're texting your significant other about buying a new pet. You're set on buying a dog, but they want a cat. You could list your reasons for wanting a dog by saying, "Puppies are sweet and smart," but concede a bit by continuing "OTOH, cats are low maintenance."
Or, say you're arguing over which president had the best hair. Your significant other might say, "I like JFK's hair the best." You might respond by saying, "I think George Washington had the best hair, but OTOH, I think that might have been a wig."