Walk into class in your underwear is to feel what the word ignominy means. Ignominy is a noun meaning great public shame, disgrace, or embarrassment, or a situation or event that causes this.
The shame can be major or minor: to suffer the ignominy of defeat/the ignominies of old age. When pronouncing this word, the main accent is on the first syllable, and the secondary accent is on the third syllable. Ignominy is from French ignominie, from Latin ignominia, formed from the prefix in- "no, not" plus nomen "a name." The corresponding English adjective is ignominious.