LOL is a verb

Well, you knew that. It's short for 'laugh out loud'. Is that a verb? Well, depends how you use it. If you mean '[I am] laughing out loud [right now]' then not really; it's a gerund or maybe a participle. But if you say 'I totally LOLed at that' then yeah, you just verbed LOL.

But I'm not talking about boring old English. In French (which, remember, people love to hold up as an example of a sensible language with a prescriptive Academie Francaise to uphold the standards of purity in the language) they've only gone and verbed it there too!

As you might expect, it's an -er verb, the 'default' conjugation (see Steven Pinker's 'Words and Rules' for a lay-person-friendly explanation of default inflections). This means you get this paradigm:

je lole
tu loles
il/elle/on lole
nous lolons
vous lolez
ils/elles lolent

(I totally just conjugated that from memory so it may not be absolutely accurate.)

Notice that this is an English acronym with French morphology applied to it. A knowledgeable colleague told me today that French has its own acronymic (yes, it's an initialism, not an acronym, whatever) equivalent of FML. It's VDM, or 'vie de merde', apparently. Go French.