“an awkward moment”
Awkward means socially uncomfortable or uneasy. It differs slightly from simply feeling embarrassed: the atmosphere itself becomes uncomfortable.
A2-40 / CEFR A2 / EPISODE 40
Talking about an embarrassing event
SceneAt a café. Frank tells Tina about an awkward moment.

WORDS & CONTEXT
Awkward means socially uncomfortable or uneasy. It differs slightly from simply feeling embarrassed: the atmosphere itself becomes uncomfortable.
Be in trouble means to be in a difficult situation; here, about to be scolded for being caught doing something wrong. When the professor read his note out loud, Frank thought he would be told off. Then everyone laughed, and his nervousness turned into relief.
Besides inspecting accounts, audit can mean to attend a university class without earning credit. Frank attends evening classes after work.
Catch someone -ing means to discover them in the act. Pass a note means to secretly hand a written message to someone during class. Frank was caught doing this by the professor.
Who are you, and what have you done with …? is a familiar joke when someone behaves unlike their usual self. Insert the person's name at the end. Tina is amazed that serious Frank passed a note in class.
Be a hit means to be very successful or popular. The noun hit can name a success. Tina is delighted that Frank's math joke made the entire class laugh.
Ate is the past tense of eat, and it sounds the same as the number eight. The wordplay is that seven ate nine sounds just like counting seven, eight, nine. The joke is that six was afraid of seven because seven is scary enough to eat nine; no math knowledge is needed.
Keep A away from B means not to let A get near B. Tina treats the number seven like a big eater and answers that she will protect her cake from it. The punchline is very Tina: she brings her favorite food into a math joke.