to boast in front of someone to impress them
sich vor jemandem aufspielen, um ihn zu beeindrucken (sich vor jemandem aufspielen, um ihn zu beeindrucken)
"He was showing off to his classmates about his new phone."
"Er gab vor seinen Klassenkameraden mit seinem neuen Telefon an." (Er gab vor seinen Klassenkameraden mit seinem neuen Telefon an.)
to persuade someone to your point of view
to have confidence in your own abilities and potential
to help someone emotionally during a difficult time
to pity or sympathize with someone or yourself
to change your opinion and agree with something eventually
to think carefully about comments or evaluations to improve