McCarthy watched his Ipswich side climb to seventh in the Championship table with a 2-1 win at Wigan Athletic on Monday.
Luke Hyam and former Wigan forward Conor Sammon scored for Ipswich, who survived a late rally from the hosts as James McClean scored before Oriol Riera hit the post.
And McCarthy put Sammon's enthusiastic celebration after scoring in the headlines when questioned about it.
The former Wolverhampton Wanderers and Sunderland manager criticised the now in-vogue practice of players refusing to celebrate after scoring against ex-clubs and said he had no hesitation on "giving it large" against teams he used to represent.
"I think that [not celebrating] is the biggest load of nonsense ever," McCarthy said.
"Are you ever going to go back and play for that club? I've had a few clubs and my club is now Ipswich.
"I'm not bothered who we're playing against. If we win, I'm giving it large.
"That's where my loyalties lie - with Ipswich."
McCarthy also hailed his side's "excellent performance" as they claimed their third win in a row.