Knocking on heaven's door
When you say Ad-nai sefatai tiftach, you are asking for Hashem to open the door to his palace. (Ad-nai gematria 'heichal'. The lips are the gates, like it says, 'pitchu li sharei tzedek'.-open the gates or righteousness for me.) The malachim then check you to see if you are dressed properly in talit and tefilin (yeladim asher ein bahem kol mum... ve'asher koach bahem la'amod lifnei hamelech - youth who are not blemished and have the wherewithal to stand in front of the king), and if you come bearing gifts (of tzedaka that you gave to poor people). -Tikun 18