Maybe it’s just me, but walking past the sign “Wet Riser” in our office stairwell always make me giggle… Are there any other totally innocent words or phrases that you can take totally out of context?
In Mexico, the little van-sized public buses called “combis” always have the following phrase painted on their rear bumpers:
Precaucion: Paradas Continuas
which literally means “Careful: Continuous Stops”, but can also be read to mean: “Caution: Continuous Boners” (as in “erections”).
Librarians use “rubber fingers”
In Physics we have
Stimulated Emission
Degenerate Perturbation Theory
Not to mention hardons.
Oops! I meant hadrons. What’s up with me and erections today?
Technical literature for commercial filtration systems make frequent use of the phrase “mother liquor”.
I’ve also gotten in trouble at work for making web searches seeking “industrial vibrators”. They attach to the sides of bins and keep material from sticking to the sides.
Wankel rotary engine
Mastication. Man, let me tell you I’m going to be masticating until I die, even if it takes artificial enhancements when I’m old. 
Some in mathematics engage in mensuration.
Back when I was in college, we got to learn all about Astable and Bistable Multivibrators
Anything said erotically enough will sound dirty- even the most innocent of phrases.
Hey, wanna mow my lawn?
Another foreign-language one:
One of the few Turkish phrases I learned in the few months I lived there was “chok guzel”, which means “very good”.
But I’d have trouble saying it to a young woman without sounding perverted:
“Choke guzzle, baby!”
Ralph Collier did a spot on these from foreign countries years ago on WFLN-FM Philadelphia. Included were gems such as (at a cleaner) “Drop your trousers here for immediate attention.” (At a hotel) “Guests are encouraged to take advantage of the chamber maids.”
Written on the boom of a crane: Steel Erection.
see www.engrish.com
Statistics lectures on the use of **copula ** functions have been known to draw a few sniggers from undergraduates.
It was really confusing reading a copy of the Guinness Book of World Records and seeing an entry for “Smallest Hadron”. Took a couple of re-readings to catch the spelling.
Do you mind if I insert my dongle?
I’ve always liked a US equivilent: “Slippery when wet”.
Yeah. . .
damn you, that was my joke!
We took a picture of a friend under a road sign in England that warned, “Humps, next five miles,” or something to that effect.
Enough about hadrons, what about Fermions?