It's another really low priced kids t-shirt, as Argos make way for the new clothing ranges that are coming in. This Angry Birds Red Go T-Shirt was £4.99, and is now half price at just £2.49.
It comes in all sizes from 4 years right up to 11 years, is 100% cotton, and is machine washable. The above link will take you to the 4 - 5 years size, so you need to use the drop down box to choose the one you need.
There are loads in stock, which may explain why they have dropped the price again, but at least that means you shouldn't have any problem getting hold of one.
As always with clothing from Argos, reserve and collect is free, or home delivery charges are from £3.95.