забивать голову or брать в голову {v. phr.} {informal}
zabivat'golovu or brat' v `golovu
{literally} to choke up one's head (with sth).
~put ideas into smb's head;
~get smt. into one's head;
Usually used in negative:
Не забивай себе этим голову! — Don't give it another thought.
Не забивать голову -
Not to pay too much attention to smt; forget abt. smt.; leave smt. alone.