Relationship friction, moral dilemmas and temptations, duty and responsibility, miscellaneous challenges

Making up an alibi to evade arrest
A young character lying to a parent, teacher, or coach to avoid consequences
The character misleading their spouse to cover up an indiscretion
Hiding a secret that could be a reputation killer
Withholding information from a co-worker or boss to avoid being fired
The character lying to protect their child
The character lying about their ideals or opinions that others would take issue with
Posing as someone in need to swindle others out of money
The character falsifying their age to purchase alcohol
Lying to a captor to gain an opportunity to escape
Traveling under a fake identity (having to answer to a different name, create and adhere to a convincing history, etc.)
The character exaggerating their financial status to obtain a vehicle or gain entry into a prestigious group
The character lying about their true feelings and intentions to a mark so they can build a relationship with them and gain access to money or other people
Fibbing to avoid hurting a friend's feelings
A politician or cult leader needing to hide their true motives and objectives from others

Having no time to prepare and having to lie on the spot
The character stumbling over their words
Someone becoming suspicious
Difficulty remembering which lies have been told to whom
A hole in the character's story being exposed
Having to lie to loved ones to hide the character's initial lie
Temporarily losing the trust of a loved one
The character's reputation being weakened when others see them lying
Needing to convince a friend to back the character up
Worry keeping the character up at night
Suffering from minor physical ailments, such as stomach pains and loss of appetite