I was watching this clip from Whose Line Is It Anyway and it was one of the picked categories.
I immediately thought of pianist, ramrod and kumquat. I know there are more, so what other words make you chuckle when they shouldn’t?
Titular.
Uranus is an obvious one.
Related to that, there’s the town of Mianus.
Niggardly tends to get shocks more than snickers, but I could see someone using it to snicker at the responses. Which is very immature. 
Penal.
Wankel Rotary Engine
Duty
Defunct
Pussy Willow
Lake Titicaca
Bobble
Infarction
Linguist
Shiitake
Pissant
Sextile
Dicker
Dickie
Fecund
Lingula
Upright
Masticate. Flocculant. Shiite. Diaresis. Cock-a-leekie. Clitic. Shittim.
Semprini 
Petcock.
Quoting George Carlin on flight decks : “Can’t imagine why they wouldn’t want to use such a lovely word as COCKPIT. Especially with all those stewardesses going in and out of it all the time.”
Member. Used often in the insurance industry, so I’m usually snickering. Just the other day a guy on the phone told me he couldn’t find his member. Not even with a microscope? It was all could do not to go all Beavis and Butthead on him.
Also testy, titillating and slot.
Ballcock.
Dongle.
Bunghole. And yes, it’s an innocent word. It’s where you place the cork, or bung, in a barrel of booze.
Uvula.
Joystick actually went the other way. It originally was dirty, then eventually wound up being the name for something children the world over used quite innocently.
Growing up near Chicago these street names get a snicker Paulina, Medina and,Hunt. (old joke)