Go ahead is something that I hear pretty frequently these days. It mightn't be very formal, but it's not negative anyways.

From LDOCE:

###go ahead phrasal verb

1 to start to do something, especially after planning it or asking permission to do it:

• go ahead and do something
  I went ahead and arranged the trip anyway.

2 ...

3 spoken used to give someone permission to do something, or let them speak before you:
'Do you mind if I open the window?' 'No, go ahead.'
If you want to leave, go right ahead.

Go ahead is something that I hear pretty frequently these days. It mightn't be very formal, but it's not negative anyways.

From LDOCE:

go ahead

phrasal verb

1 to start to do something, especially after planning it or asking permission to do it:

• go ahead and do something
  I went ahead and arranged the trip anyway.

2 ...

3 spoken used to give someone permission to do something, or let them speak before you:
'Do you mind if I open the window?' 'No, go ahead.'
If you want to leave, go right ahead.