The words спех and спешка are nouns that mean “a hurry, a rush.” They are conversational words; you wouldn't write them in a formal paper. The former is particularly used in combination with the preposition к to mean “to be in a rush/hurry (to get something, to get something done).” The person who feels the haste is expressed in the dative:

Спешка is mostly used in the prepositional case after в:

The Russian word for forehead is лоб. The о is a fleeting vowel, which means that any time you add a grammatical ending to the noun, the о drops out. Notice also that the word distinguishes a locative form «на лбу» “on the forehead” from the prepositional form «о лбе» “about the forehead.”

Of course, in that last example they have in mind a statue of Lenin, not Lenin's embalmed body.

There is a phrase «как на лбу написано» “like it was written on the forehead” that the Russians use to catch the idea that something was obvious by the expression of a person's face.

Have you ever wondered where the word muscle comes from? It's from Latin. In Latin mūs means mouse. The suffix -culus is a diminutive suffix. Thus mūsculus means “little mouse,” which kind of makes sense since if you look at a muscle moving on your body, it kind of looks like some critter is scurrying under your skin. In Russian the root мыш- means mouse. The suffix -ца is a diminutive suffix. One of the words for muscle in Russian is мышца. When you take the roots and suffixes of a word in one language, and you substitute the roots and suffixes of another language to make a new word in that language, we call that word a calque. Мышца is a Russian calque from a Latin word. Interestingly enough, something similar happens in Polish. The Polish root for mouse is myš-, and -ca is a diminutive suffix. The Polish word myšca is also a calque from Latin and means muscle. Here are some sample sentences:

Подмышка is a fun word. The prefix под- means under, and the root мыш- means mouse. Thus подмышка means armpit, and doesn't that little bit of hair under your arm kind of look like a mouse? Sample sentences:

¹ From the movie “Flirting with Disaster.”

Мышь also means mouse in the sense of a computer mouse. There are a lot of different kinds of mouses (mice?) out there, including:

When you talk about pressing a mouse button, a variety of verbs are used: нажимать/нажать “to press,” кликать/кликнуть “to click,” щелкать/щелкнуть “to click.” Sample sentences:

¹ Examples adapted from this source.