Air carrier flight crew reported during initial approach they were instructed to go around due to reported FOD on the runway. As they were initiating the go around; they did not raise the flaps and they got a landing gear aural warning.

Narrative

During our approach to RWY 27C the preceding aircraft notified ATC of FOD on the runway as they were clearing the runway. We were given instructions to execute a go around at about 300ft AGL. I called for go around toga and began executing the go around. During this the PM was answering the radio and clarifying an instruction given by ATC. During this the call out for flaps 2 was not correctly communicated; because when he got finished with the radios he called positive rate and I responded with gear up. Soon we got the landing gear" aural warning and that is when I realized we had not gotten the flaps to 2. We corrected this by bringing he flaps to 2; and continued to climb out and accelerate to 210kts. We received vectors for a new approach to 27L and landed without further event.Suggestion: Continue to encourage crews to communicate clearly and verify actions during high work load periods. Remind crews to always be ready; and anticipate a go around in order to help mitigate the effects of being surprised or caught off guard."