What to say about “Deadpool 2” that won’t step on the self-referential jokes that make up most of its running time? Very little, and I would never do that, even if I hadn’t been expressly warned not to in a jokey pre-screening PSA from star Ryan Reynolds.

In the most carefully vague of terms, I can report that the sequel to Reynolds’ raunchy, violent 2016 comedy succeeds at being bigger-scale and funnier, if lacking the novelty of the original’s gleeful irreverence. It’s also got a terrific blink-and-you’ll-miss-it cameo.

Last time, we got the origin story of Wade Wilson, a sardonic mercenary turned superpowered mutant. Freed from the gritty process of retracing Wade/Deadpool’s literally torturous past, this film doubles down on its best asset — R-rated humor — while giving its leading man a bit more heart (a claim to which the character would no doubt object).

The plot follows our ’80s-ballad-loving protagonist on a mission to save a young mutant, the 14-year-old Russell (Julian Dennison) from a time-traveling killer named Cable (Josh Brolin).

You may notice something familiar about Cable, and that’s because Brolin also plays the supervillain Thanos in Marvel’s “Avengers: Infinity War,” still in theaters. Reportedly there was an extensive casting search which eventually landed on Brolin, who is a very good actor and indeed good in this part.

His Thanos, meanwhile, is disguised under motion-capture animation, so yes, they’re different. But seriously? Brolin is not the only big, beefy, dramatically talented game in town, surely. There’s at least one dig at the Thanos overlap (“Deadpool” is also Marvel), but the doubled-up casting still seems . . . odd.

Returning are Morena Baccarin as Wade’s unflappable partner and Karan Soni as his loyal, cab-driving sidekick. Kiwi actor Dennison is great as an angry, fire-powered mutant on the warpath, and he handily swaps off-color banter with Reynolds as the two are carted off, at one point, to a calamitous mutant prison.

Also reprising roles from the original are two X-Men, Colossus (voice of Stefan Kapicic) and Negasonic Teenage Warhead (Brianna Hildebrand), now joined by others in an X-Men offshoot team called X-Force (the unoriginality of which doesn’t escape the writers’ poison pens).

The scribes — Rhett Reese, Paul Wernick and now Reynolds himself — have an especially good time with Deadpool’s recruitment effort: Some newcomers, like Bedlam (Terry Crews), Domino (Zazie Beetz), Zeitgeist (Bill Skarsgård) and a blank space called The Vanisher, exist in Marvel comics lore. Then there is, delightfully, a random guy named Peter (“Catastrophe” comic Rob Delaney).

The writers also top the first film’s post-credits sequence, a “Ferris Bueller” homage, with a more extensive gag that earned the most sustained laughter out of my screening audience (and that’s saying something).

“John Wick” and “Atomic Blonde” director David Leitch, taking over for the original’s Tim Miller, brings competent polish to big set pieces, though none quite measure up to the “Angel of the Morning”-scored opening scene of the first film.

If you’ve got comics-movie fatigue, “Deadpool 2” is here for you, with frequent fourth-wall breaks to point out lazy writing, blatant foreshadowing or heavy reliance on CGI for fight scenes. That doesn’t mean those things aren’t there (they are) — but the eagerness of “Deadpool” to call out its own shortcomings earns this trash-talking franchise a lot of goodwill.