I'll fix it this way:
CREATE TABLE foob(id serial primary key, name varchar default '');
CREATE TABLE fooA(id serial primary key, fooBook int not null
references fooB(id) on update cascade on delete cascade DEFERRABLE,
name varchar default '');
CREATE FUNCTION foobarrB() RETURNS trigger AS
$_$
BEGIN
BEGIN
INSERT INTO foob_temp(id, name) VALUES(OLD.id, OLD.name);
EXCEPTION
WHEN undefined_table THEN
CREATE TEMP TABLE foob_temp(id bigint not null, name varchar not
null) ON COMMIT DROP;
INSERT INTO foob_temp(id, name) VALUES(OLD.id, OLD.name);
END;
RETURN OLD;
END;
$_$ LANGUAGE 'plpgsql';
CREATE TRIGGER foobbrrrred BEFORE DELETE ON fooB FOR EACH ROW EXECUTE
PROCEDURE foobarrB();
CREATE FUNCTION foobarrA() RETURNS trigger AS
$_$
DECLARE
_name varchar;
BEGIN
BEGIN
SELECT name INTO _name FROM foob_temp WHERE id = OLD.fooBook;
EXCEPTION
WHEN undefined_table THEN
SELECT name INTO _name FROM fooB WHERE id = OLD.fooBook;
END;
RAISE NOTICE 'foobarred %', _name;
RETURN OLD;
END;
$_$ LANGUAGE 'plpgsql';
CREATE TRIGGER fooaarrrred BEFORE DELETE ON fooA FOR EACH ROW EXECUTE
PROCEDURE foobarrA();
insert into foob(name) select random()::varchar FROM generate_series(1,1000);
insert into fooa(name, fooBook) select random()::varchar, bb.id FROM
(select id from foob order by random() limit 1) bb,
generate_series(1,100);
DELETE FROM foob where id in (select foobook from fooa order by
random() limit 3);