Ipso was an Irish made breath mint that was popular in the UK in the 1970s and '80s and was briefly sold in the US. They came in Peppermint, Orange, Lime and Raspberry flavours. Spearmint and Cinnamon replaced Lime and Raspberry in the US.
They were most famous for their Lego-like boxes, which you could collect and stack. However, they had a very special use for drug users, who used them as stash boxes, leading to many American schools banning them. But overall, they never sold well in America and disappeared from US shelves by 1981. They lasted until the late 1980s in the UK.
They never had a large advertising presence in the US, but in the UK, they were noted for this classic TV ad.