Adverb
in a violent or sudden or noisy manner
directly or immediately
Source: WordNetslap-bang
It always depresses me when people moan about how commercial Christmas is. I love everything about it. The tradition of having this great big feast, slap bang in the middle of winter, is an essential thing to look forward to at the end of the year. Richard E. Grant
the pans fell slam-bang and woke the whole house Source: Internet
it hit slap-bang in the middle Source: Internet