There are words in language which, while they have sexual denotations--especially in this sexually-orientated modern culture--also have other meanings. Such a word as "pregnant" is used most often to denote the physical development of a baby in a woman's womb. However, one can refer to a statement as being pregnant with meaning. Here the definition is that the statement is highly significant.
Now, let us examine the words from "The Cask of Amontillado" within their context for meaning, keeping in mind, also, that this is NOT a modern story, having been published in 1846. As Montesor leads his victim farther into the catacombs, he describes this area:
Three sides of this interior crypt were still ornamented in this manner. From the fourth the bones had been thrown down, and lay promiscuously upon the earth, forming at one point a mound of some size.
As the depth of recess gets darker, the light does not help them to see. In order to distract Fortunato, Montesor makes reference to Fortunato's rival, Luchesi, angering his victim. Montesor fetters Fortunato to the granite wall, saying,
'Pass you hand,' I said, 'over the wall; you cannot help feeling the niter. Indeed it is very damp. Once more let me implore you to return. No? then I must positively leave you. But I must first render you all the little attentions in my power.'
Confused by Montesor's tettering him to the wall while at the same time acting concerned for his health, and then saying he must leave, Fortunato attempts to distract Montesor and redirect him to taking him to the wine cask, the reason for their entering the catacombs:
'The Amontillado!' ejaculated my friend, not yet recovered from his astonishment.
Thus, the reader can perceive that within the context of Poe's story, promiscuously denotes "involving indiscriminate mingling"--the bones were scattered about--and ejaculated denotes "uttered suddenly and briefly; exclaimed." (That this word follows a quotation leaves no doubt as to its meaning.)
Nevertheless, there are always the connotations of words to consider. And, since Montesor is "consumed by the lust of hate" as D.H. Lawrence (Studies in Classic American Literature) comments, there may have been some intention on Poe's part to use words with sexual overtones to suggest this hatred that is lustful, or so passionate that it is overmastering in its desire.
So, you may wish to research D. H. Lawrence who theorized that all drives of men and women emanated from sexual desire and expression. An interesting angle to this story, indeed.
Good observation on your part! Notwithstanding, D. H. Lawrence once stated: "A word does not make a theme." And, it is not likely a writer uses words unintentionally. So it is not a coincidence that the words are where they are, nor is it a coincidence that he used precisely those words. The real question becomes, "What can these words possibly lead to?"
Can you find other evidence in the story, that along with your observations of those two words, form an arguable thesis or point that Poe was trying to make? Can those words also mean something less sexual, or something different as used in the time and setting in which he wrote?
I am not sure which grade you are in, but a paper in which you argue that there is another dimension to his work, a sexual one, would make for an interesting research paper that anyone would be willing to read.