Dave Ramsey uses the term "Ramsey-ish" (or simply "-ish") to describe any program that doesn't follow 100% what he believes and teaches. When deriding -ish, Ramsey incorporates two logical fallacies into the discussion: the false dichotomy and the straw man.
A logical fallacy is the use of invalid or faulty reasoning in an argument. Fallacies are often used intentionally and deceptively to manipulate or persuade others. Everyone has experienced fallacies, even if they don't know the name of them. The most common is the ad hominem attack where the user attacks the other person directly rather than the other person's argument. "Yeah, but you're an idiot," is how it sounds in use.
When arguing about -ish, Ramsey first uses what's called the false dichotomy (also called the either/or fallacy or false dilemma) to indicate that his program is the only viable way of doing things. This is an error in argument where only two options are presented even though more exist. These options are also mutually exclusive--you can't pick both. Ramsey says, "Either you do my program and succeed or do it your way and fail." This is classic false dichotomy with no attempt by Ramsey to even hide it.
Second, Ramsey's term Dave-ish incorporates the straw man fallacy. This one's a bit more complicated and well-disguised. A person who uses the straw man fallacy appears to refute an argument through a stronger counterargument, but actually attacks a weaker or constructed version of the original argument. This "straw man" is easier to defeat, but must first be built undetected during the argument.
Here's how Dave Ramsey builds his straw man:
Ramsey abhors anything that he doesn't agree with, regardless of its viability (e.g., Debt Avalanche, credit card usage, and judicious use of credit for necessary things). It's hard, if not impossible, to attack some of these concepts head-on because the logic supporting them is far too strong for him. Instead, Ramsey has to build something that can be easily attacked--a straw man.
Ramsey builds his straw man and calls it "-ish". Ish, according to Ramsey, is spending more than you make, impulse buying on credit, leasing cars or buying them new and taking a big hit on depreciation the minute you drive them off the lot, using payday loans, using buy now, pay later and letting the interest accrue, investing while on Baby Step 2...ad nauseam. He also thrown in a barrage of cutesy marketing slogans to help obscure the battlefield as he builds the straw man he'll attack later.
Once Ramsey has his straw man built, he holds it in reserve for anyone who dares challenge his Total Money Makeover or Baby Steps. When someone successfully argues that credit cards can be used responsibly just as any other tool or that the Debt Avalanche can be used as effectively as the Debt Snowball as long as you don't need the psychological quick wins, Ramsey summons the straw man and demonstrates how weak it is by destroying it. He then says, "You're ish" and therefore what he just destroyed is you.
Did you catch it? Ramsey doesn't attack the argument about credit cards. He attacks all of the things he's attached to his straw man (ish), thus defeating it. When he associates your plan with the straw man, it "proves" that what you're doing doesn't work.
It's tricky, but once you recognize how Ramsey uses fallacies to manipulate his followers, you'll know that what he's saying a bunch of bullshit.
And the image is obviously a joke. No disrespect to Larry intended.